Photo credit: Karim-Aly Kassam
Special Issue : Rhythms of the Earth
Indigenous and rural societies that have contributed least to the anthropogenic climate crises are facing its harshest consequences. One of the greatest challenges is the lack of predictability, especially at local scales. Indigenous and rural societies face an ever shifting “new normal” through increasing inconsistency in the seasonality of temperature and precipitation, and greater frequency of extreme weather events. With global food systems dependent on local producers, climatic variability disrupts access to affordable, nutritious, and culturally relevant food. Social and biophysical scientists are collaborating with communities to build revitalized ecological calendars based on a combination of Indigenous and scientific ecological knowledge, thus contributing to anticipatory capacity. This special issue:
- Communicates research findings from diverse sociocultural and ecological contexts
- Presents replicable participatory research methodologies
- Demonstrates the global applicability of ecological calendars to build anticipatory capacity
- Articulates policy and adaptation strategies
- Engages diverse perspectives
Role of biodiversity in ecological calendars and its implications for food sovereignty: Empirical assessment of the resilience of indicator species to anthropogenic climate change.
Kassam, K.-A. S., & Bernardo, J. (2022). Role of biodiversity in ecological calendars and its implications for food sovereignty: Empirical assessment of the resilience of indicator species to anthropogenic climate change. GeoHealth, 6, e2022GH000614. https://doi.org/10.1029/2022GH000614
Adaptation-Mitigation Binary Outlived its Value? Indigenous Ways of Knowing Present an Alternative.
Ullmann, A. & Kassam, K-A. (2022). Has the Adaptation-Mitigation Binary Outlived its Value? Indigenous Ways of Knowing Present an Alternative. Community Science, 1, e2022CSJ000008.
Curating an Exhibition about Place-rooted Ecological Knowledge
Avril, E., Weislogel, A. C., Frankel, K. A., Yearsley, E., & Chu, J. (2022). Curating an Exhibition about Place‐rooted Ecological Knowledge. GeoHealth, e2022GH000625.
Interpreting Ecological Calendars for the Public Through Exhibits, Art, and Education
Skelly, S. M., Fiorello, S., Potter, J., Sun, W., & Hull, S. (2022). Interpreting ecological calendars for the public through exhibits, art, and education. GeoHealth, e2022GH000622.
Other Articles and Book Chapters:
Medicinal Plants and Health Sovereignty in Badakhshan, Afghanistan: Diversity, Stewardship, and Gendered Knowledge
Karamkhudoeva, M., Laldjebaev, M., Ruelle, M. & Kassam, K.-A. (2021). Medicinal Plants and Health Sovereignty in Badakhshan, Afghanistan: Diversity, Stewardship, and Gendered Knowledge. Human Ecology, 49(6), 809-829. DOI: 10.1007/s10745-021-00270-9.
Engaging Transformation: Using Seasonal Rounds to Anticipate Climate Change
Kassam, K.-A., Ruelle, M., Haag, I., Bulbulshoev, U., Kaziev, D., Louis, L., Ullmann, A., Edwards, I., Khan, A. A., Trabucco, A., & Samimi, C. (2021). Engaging transformation: Using seasonal rounds to anticipate climate change. Human Ecology, 49(5), 509–523. https://doi.org/10.1007/s10745-021-00269-2.
Transdisciplinary research, Indigenous knowledge, and wicked problems
Kassam, K.-A. (2021). Transdisciplinary Research, Indigenous Knowledge, and wicked problems. Rangelands, 43(4), 133–141. https://doi.org/10.1016/j.rala.2021.04.002.
Incorporating Biocultural Approaches in Forest Management: Insights from a Case Study of Indigenous Plant Stewardship in Maine, USA and New Brunswick, Canada
Baumflek, M., Kassam, K-A., Ginger, C., & Emery, M. R. (2021). Incorporating Biocultural Approaches in Forest Management: Insights from a Case Study of Indigenous Plant Stewardship in Maine, USA and New Brunswick, Canada. Society & Natural Resources, DOI: 10.1080/08941920.2021.1944411.
Anthropogenic Climate Change, Anxiety, and the Sacred: The Role of ecological calendars in the Pamir Mountains of Central Asia
Kassam, K-A. (2021). Anthropogenic Climate Change, Anxiety, and the Sacred: The Role of ecological calendars in the Pamir Mountains of Central Asia (Chapter 6). In D. Haberman (Ed.), Understanding climate change through religious lifeworlds, 153-179. Bloomington, IN: Indiana University Press. https://doi.org/10.2307/j.ctv21hrh8r.10
Measurements meet human observations: integrating distinctive ways of knowing in the Pamir Mountains of Tajikistan to assess local climate change
Haag, I., Kassam, K.-A., Senftl, T., Zandler, H., & Samimi, C. (2021). Measurements meet human observations: Integrating distinctive ways of knowing in the Pamir Mountains of Tajikistan to assess local climate change. Climatic Change, 165(1-2). https://doi.org/10.1007/s10584-021-02988-3
Using Research to Support Transformative Impacts on Complex, “Wicked Problems” With Pastoral Peoples in Rangelands
Reid, R. S., Fernández-Giménez, M. E., Wilmer, H., Pickering, T., Kassam, K.-A. S., Yasin, A., Porensky, L. M., Derner, J. D., Nkedianye, D., Jamsranjav, C., Jamiyansharav, K., Ulambayar, T., Oteros-Rozas, E., Ravera, F., Bulbulshoev, U., Kaziev, D. S., & Knapp, C. N. (2021). Using Research to Support Transformative Impacts on Complex, “Wicked Problems” With Pastoral Peoples in Rangelands. Frontiers in Sustainable Food Systems, 4, 273. DOI: 10.3389/fsufs.2020.600689
Science with Society: Evidence-based Guidance for Best Practices in Environmental Transdisciplinary Work
Steger, C., Klein, J. A., Reid, R. S., Lavorel, S., Tucker, C., Hopping, K. A., Marchant, R., Teel, T., Cuni-Sanchez, A., Dorji, T., Greenwood, G., Huber, R., Kassam, K-A., Kreuer, D., Nolin, A., Russell, A., Sharp, J., Hribar, M. Š., Thorn, J. P. R., Grant, G., Mahdi, M., Moreno, M., Waiswa, D. (2021). Science with society: Evidence-based guidance for best practices in environmental transdisciplinary work. Global Environmental Change, 68, 102240. https://doi.org/10.1016/j.gloenvcha.2021.102240
The IPBES Global Assessment: Pathways to Action
Ruckelshaus, M. H., Jackson, S. T., Mooney, H. A., Jacobs, K. L., Kassam, K.-A. S., Arroyo, M. T. K., Báldi, A., Bartuska, A. M., Boyd, J., Joppa, L. N., Kovács-Hostyánszki, A., Parsons, J. P., Scholes, R. J., Shogren, J. F., & Ouyang, Z. (2020). The IPBES Global Assessment: Pathways to Action. Trends in Ecology & Evolution, 35(5), 407–414. https://doi.org/10.1016/j.tree.2020.01.009
Ökologische Kalender im Pamir: Anpassung an den Klimawandel auf dem Dach der Welt
Haag, I., Kassam, K-A., Samimi, C. (2019). Ökologische Kalender im Pamir: Anpassung an den Klimawandel auf dem Dach der Welt. Geographische Rundschau, 12, 26-31. ISSN 0016-7460
Biocultural diversity and food sovereignty: A case study of human-plant relations in northwestern Ethiopia
Ruelle, M.L., Kassam, K-A., Morreale, S.J., Asfaw, Z., Power, A.G., Fahey, T.J. (2019). Biocultural diversity and food sovereignty: A case study of human-plant relations in northwestern Ethiopia. Food Security, 11(1), 183-199. https://doi.org/10.1007/s12571-019-00888-0
Grassroots Stewardship in Iran: The Rise and Significance of Nature Cleaners
Kassam, K-A, Golshani, Z., Krasny, M.E. 2018. Grassroots Stewardship in Iran: The Rise and Significance of Nature Cleaners. In Grassroots to Global: Broader Impacts of Civic Ecology. M.E. Krasny (Editor). Ithaca: Cornell University Press. 65-84.
Anticipating Climatic Variability: The Potential of Ecological Calendars
Kassam, K-A.S., Ruelle, M.L., Samimi, C. Trabucco, A. Xu, J. 2018. Anticipating Climatic Variability: The Potential of Ecological Calendars. Human Ecology, 46(2): 249-257. Online: https://doi.org/10.1007/s10745-018-9970-5
Rethinking energy security and services in practice: National vulnerability and three energy pathways in Tajikistan
Laldjebaev, M., Morreale, S. J., Sovacool, B. K., & Kassam, K.-A. S. (2018). Rethinking energy security and services in practice: National vulnerability and three energy pathways in Tajikistan. Energy Policy, 114, 39–50. https://doi.org/10.1016/j.enpol.2017.11.058
Human ecology of sacred space: Church forests in the highlands of northwestern Ethiopia
Ruelle, M.L., Kassam, K-A., Asfaw, Z. (2017). Human ecology of sacred space: Church forests in the highlands of northwestern Ethiopia. Environmental Conservation, 1-10. DOI: 10.1017/S0376892917000534
The cognitive relevance of Indigenous and rural: Why is it critical to survival?
Kassam, K-A.S., Avery, L.M., & Ruelle, M.L. (2017). The cognitive relevance of Indigenous and rural: Why is it critical to survival? Cultural Studies in Science Education (CSSE) Special Issue on Rural Science Education, 12: 97-118. DOI:10.1007/s11422-016-9745-5
Toward a national, sustained U.S. ecosystem assessment: Pieces are in place, but need coordination and policy focus
Jackson, S.T., Duke, C.S., Hampton, S.E., Jacobs, K.L., Joppa, L.N., Kassam, K-A.S., Mooney, H.A., Ogden, L.A., Ruckelshaus, M., Shogren, J.F. (2016). Toward a national, sustained U.S. ecosystem assessment: Pieces are in place, but need coordination and policy focus. Science, 354 (6314): 838-839. DOI: 10.1126/science.aah5750
Government: Plan for ecosystem services
Joppa, L., Boyd, J., Duke, C., Hampton, S., Jackson, S., Jacobs, K., Kassam, K-A., Mooney, H., Ogden, L., Ruckelshaus, M., & Shogren, J. (2016). Government: Plan for ecosystem services. Science, 351(6277): 1037. DOI: 10.1126/science.351.6277.1037-a
Sociocultural and Ecological Systems of Pastoralism in Inner Asia: Cases from Xinjiang and Inner Mongolia in China and the Pamirs of Badakhshan, Afghanistan
Kassam, K-A., Liao, C., & Dong, S. (2016). Sociocultural and Ecological Systems of Pastoralism in Inner Asia: Cases from Xinjiang and Inner Mongolia in China and the Pamirs of Badakhshan, Afghanistan (Chapter 4). In Building Resilience of Human-Natural Systems of Pastoralism in the Developing World: Interdisciplinary Perspectives. S. Dong, K-A. Kassam, J. Tourrand, R. Boone (Editors). New York: Springer. 137-175. https://doi.org/10.1007/978-3-319-30732-9_4
In Building Resilience of Human-Natural Systems of Pastoralism in the Developing World: Interdisciplinary Perspectives
Kassam, K-A. 2016. Conclusion (Chapter 8). Building Resilience of Human-Natural Systems of Pastoralism in the Developing World: Interdisciplinary Perspectives. S. Dong, K-A. Kassam, J. Tourrand, R. Boone (Editors). New York: Springer. 281-284. https://doi.org/10.1007/978-3-319-30732-9_8
The cognitive relevance of Indigenous and rural: Why is it critical to survival?
Kassam, K-A., Avery, L., & Ruelle, M. (2016). The cognitive relevance of Indigenous and rural: Why is it critical to survival?. Cultural Studies of Science Education, online: 1-22. https://doi.org/10.1007/s11422-016-9745-5
Indigenous ecological knowledge as the basis for adaptive environmental management: Evidence from pastoralist communities in the Horn of Africa
Liao, C., Ruelle, M., & Kassam, K-A. (2016). Indigenous ecological knowledge as the basis for adaptive environmental management: Evidence from pastoralist communities in the Horn of Africa. Journal of Environmental Management, 182: 70-79. https://doi.org/10.1016/j.jenvman.2016.07.032
Energy security, poverty, and sovereignty: Complex interlinkages and compelling implications
Laldjebaev, M., Sovacool, B., & Kassam, K-A. (2016). Energy security, poverty, and sovereignty: Complex interlinkages and compelling implications (Chapter 7). In Guruswamy, L. (Ed.) International Energy and Poverty: Emerging Contours. London: Routledge. 97-112.
Engendering a new generation of public intellectuals: Speaking truth to power with grace and humility
Kassam, K-A. (2015). Engendering a new generation of public intellectuals: Speaking truth to power with grace and humility (Chapter 6). In M. Keren and R. Hawkins (Editors), Speaking Power to Truth: Digital Discourse and the Public Intellectual, Athabasca University Press. 129-154.
Does diversification improve livelihoods? Pastoral households in Xinjiang, China
Liao, C., Barrett, C., & Kassam, K-A. (2015). Does diversification improve livelihoods? Pastoral households in Xinjiang, China. Development and Change, 46(6): 1302-1330. https://doi.org/10.1111/dech.12201
The promise and peril of intensive-site-based ecological research: Insights from the Hubbard Brook ecosystem study
Fahey, T.J., Templer, P.H., Anderson, B.T., Battles, J.J., Campbell J.L., Driscoll, C.T., Fusco, A.R., Green, M.B., Kassam, K-A., Rodenhouse, N. L., Rusted, L., Schaberg, P.G., & Vadeboncoeur, M.A. (2015). The promise and peril of intensive-site-based ecological research: Insights from the Hubbard Brook ecosystem study (ESA Centennial Paper). Ecology, 96(4): 885-901. https://doi.org/10.1890/14-1043.1
Habitat modeling for health sovereignty: Increasing indigenous access to medicinal plants in northern Maine, USA
Baumflek, M., DeGloria, S., & Kassam, K-A. (2015). Habitat modeling for health sovereignty: Increasing indigenous access to medicinal plants in northern Maine, USA. Applied Geography, 56, 83-94. https://doi.org/10.1016/j.apgeog.2014.10.012
Revisiting the image of limited good on sustainability, thermodynamics, and the illusion of creating wealth
Kassam, K-A. 2015. Comment on “Revisiting the image of limited good on sustainability, thermodynamics, and the illusion of creating wealth” by P. Trawick & A. Hornborg. Current Anthropology, 56(1): 1-27. Comment is on pages 20-21.
Following the green: Coupled pastoral migration and vegetation dynamics in the Altay and Tianshan Mountains of Xinjiang, China
Liao, C., Morreale, S. J., Kassam, K-A., Sullivan, P. J., & Fei, D. (2014). Following the green: Coupled pastoral migration and vegetation dynamics in the Altay and Tianshan Mountains of Xinjiang, China. Applied Geography, 46: 61-70. https://doi.org/10.1016/j.apgeog.2013.10.010
Foodways transmission in the Standing Rock Nation
Ruelle, M. and Kassam, K-A. (2013). Foodways transmission in the Standing Rock Nation. Food and Foodways, 21(4): 315-339. https://doi.org/10.1080/07409710.2013.850007
Socioenvironmental threats to pastoral livelihoods: Risk perceptions in the Altay and Tianshan Mountains of Xinjiang, China
Liao, C., Sullivan, P. J., Barrett, C. B., & Kassam, K.-A. S. (2013). Socioenvironmental threats to pastoral livelihoods: Risk perceptions in the Altay and Tianshan Mountains of Xinjiang, China. Risk Analysis, 34(4), 640–655. https://doi.org/10.1111/risa.12146
Global assemblages, resilience, and Earth stewardship in the Anthropocene
Ogden, L., Heynen, N., Oslender, U., West, P. Kassam K-A., & Robbins, P. (2013). Global assemblages, resilience, and Earth stewardship in the Anthropocene. Frontiers in Ecology and Environment, 11(7): 341-347. DOI:10.1890/120327
The oikos of rural children: A lesson for the adults in experiential education
Kassam, K.-A. and Avery, L. (2013). The oikos of rural children: A lesson for the adults in experiential education. The Journal of Sustainability Education.
Keeping all the parts: Adaptation amidst dramatic Change in the Pamir Mountains
Kassam, Karim-Aly. (2013). Keeping all the parts: Adaptation amidst dramatic Change in the Pamir Mountains. Continuity and Change in Cultural Adaptation of Mountain Environments, Studies in Human Ecology and Adaptation 7. Ed. L. R. Lozny. New York: Springer Science + Business Media. 303-317. DOI: 10.1007/978-1-4614-5702-2_12
Agrobiodiversity shifts on three continents since Vavilov and Harlan: Assessing causes, processes, and implications for food security
Nabhan, G. P., Wilson, K., Aknazarov, O., Kassam, K-A., Monti, L., Cavagnaro, D., Kelly, S., Johnson, T., & Sekacucu, F. (2012). Agrobiodiversity shifts on three continents since Vavilov and Harlan: Assessing causes, processes, and implications for food security. Biodiversity in Agriculture: Domestication, Evolution, and Sustainability. Ed. Paul Gepts et al. Cambridge: Cambridge University Press. 407-425.
Ecology of Time: Calendar of the Human Body in the Pamir Mountains
Kassam, K.-A., Bulbulshoev, U., & Ruelle, M. (2011). Ecology of time: Calendar of the human body in the Pamir Mountains. Journal of Persianate Studies, 4(2), 146–170. https://doi.org/10.1163/187471611×600369
Human ecology of vulnerability and adaptation: Case studies of climate change from high latitudes and altitudes
Kassam, K.-A., Baumflek, M., Ruelle, M., and Wilson, N. (2011). Human ecology of vulnerability and adaptation: Case studies of climate change from high latitudes and altitudes. Climate Change – Socioeconomic Effects. Ed. J. Blanco & H. Kheradmand. InTech Open Access Publishers. 217-236.
Practicing food sovereignty: Spatial analysis of an emergent food system for the Standing Rock Nation
Ruelle, M., Morreale, S., & Kassam, K.-A. (2011). Practicing food sovereignty: Spatial analysis of an emergent food system for the Standing Rock Nation. Journal of Agriculture, Food Systems, and Community Development, 163–179. https://doi.org/10.5304/jafscd.2011.021.005
Diversity of plant knowledge as an adaptive asset: A case study with Standing Rock Elders
Ruelle, M. L., & Kassam, K-A. (2011). Diversity of plant knowledge as an adaptive asset: A case study with Standing Rock Elders. Economic Botany, 65(3), 295–307. https://doi.org/10.1007/s12231-011-9168-x
Phronesis: Children’s local rural knowledge of science and engineering
Avery, L. M., & Kassam, K.-A. (2011). Phronesis: Children’s local rural knowledge of science and engineering. Journal of Research in Rural Education, 26(2), 1-18. Retrieved from http://jrre.psu.edu/articles/26-2.pdf
Medicinal plant use and health sovereignty: Findings from the Tajik and Afghan Pamirs
Kassam, K.-A., Karamkhudoeva, M., Ruelle, M., & Baumflek, M. (2010). Medicinal plant use and health sovereignty: Findings from the Tajik and Afghan Pamirs. Human Ecology, 38(6), 817–829. https://doi.org/10.1007/s10745-010-9356-9
Pluralism, resilience, and the ecology of survival: Case studies from the Pamir Mountains of Afghanistan
Kassam, Karim-Aly. (2010). Pluralism, resilience, and the ecology of survival: Case studies from the Pamir Mountains of Afghanistan. Ecology & Society, 15(2): 8. https://doi.org/10.5751/es-03485-150208
Practical wisdom and ethical awareness through student experiences of development
Kassam, Karim-Aly. (2010). Practical wisdom and ethical awareness through student experiences of development. Development in Practice, 20(2): 205-218. https://doi.org/10.1080/09614520903564207
Coupled socio-cultural and ecological systems at the margins: Arctic and Alpine cases
Kassam, Karim-Aly. (2010). Coupled socio-cultural and ecological systems at the margins: Arctic and Alpine cases. Frontiers of Earth Science in China, 4(1): 89-98. https://doi.org/10.1007/s11707-010-0008-6
Viewing change through the prism of Indigenous human ecology: Findings from the Afghan and Tajik Pamirs
View Article (Cover and Lead Article)
Kassam, Karim-Aly. (2009). “Viewing change through the prism of Indigenous human ecology: Findings from the Afghan and Tajik Pamirs” Human Ecology, 37(6): 677-690. https://doi.org/10.1007/s10745-009-9284-8
Diversity as if Nature and Culture Matter: Biocultural Diversity and Indigenous Peoples
Kassam, Karim-Aly. (2008). Diversity as if Nature and Culture Matter: Biocultural Diversity and Indigenous Peoples. International Journal of Diversity in Organizations, Communities and Nations, 8(2): 87-95. http://dx.doi.org/10.11575/PRISM/35440
Fière: Effective Practices in Self-Help Institutions
Kassam, Karim-Aly. (2007). “Fière: Effective Practices in Self-Help Institutions” My Society, 1(1): 17-38.
Human Ecology
Kassam, Karim-Aly. (2005). Human Ecology. Encyclopaedia of the Arctic (3 Volumes). Ed. Mark Nuttal. New York: Routledge. 892-896.
Hunting, Subsistence
Kassam, Karim-Aly. (2005). Hunting, Subsistence. Encyclopedia of the Arctic (3 Volumes). Ed. Mark Nuttal. New York: Routledge. 899-902.
Muslim Presence in Alberta: Contributions and Challenges
Kassam, Karim-Aly. (2005). “Muslim Presence in Alberta: Contributions and Challenges.” In Chinook Country Remembered. Calgary: Chinook (Alberta) Historical Society. 183-195. http://dx.doi.org/10.11575/PRISM/35441
Academics as Citizens – Collaborative Interdisciplinary Research in the Service of Communities
Kassam, Karim-Aly and Wisdom Tettey. (2003). Academics as Citizens – Collaborative Interdisciplinary Research in the Service of Communities. Canadian Journal of Development Studies, 24(1): 155-174. http://dx.doi.org/10.11575/PRISM/35436
On Being a Canadian Muslim Post September 11th
Kassam, Karim-Aly. (2002). On Being a Canadian Muslim Post September 11th. Kassam, Karim-Aly, George Melnyk, and Lynne Perras (editors). Canada and September 11th: Impact and Responses. Calgary: Detselig. 185-193.
Life North of 60°: Homeland or Frontier?
Kassam, Karim-Aly. (2001). Life North of 60°: Homeland or Frontier? Passion for Identity: Canadian Studies for the 21st Century. Scarborough: Nelson Thompson Learning. 433-455. https://doi.org/10.11575/PRISM/35442
Indigenous, Cartesian and Cartographic: Visual Metaphors of Knowledge in Arctic (Tundra) and Sub-Arctic (Taiga) Communities
Kassam, Karim-Aly and Sean Maher. (2000). Indigenous, Cartesian and Cartographic: Visual Metaphors of Knowledge in Arctic (Tundra) and Sub-Arctic (Taiga) Communities. Links Between Cultures and Biodiversity. Kunming (China): Yunnan Science and Technology Press. 785-811.
Indigenous Knowledge, Community Participation and Traditional Land-Use Mapping
Kassam, Karim-Aly and John Graham. (1999). Indigenous Knowledge, Community Participation and Traditional Land-Use Mapping. In Delaney, R., Brownlee, K., & Sellick, M. (Eds.), Social Work with Rural and Northern Communities. Thunder Bay: Centre for Northern Studies, Lakehead University. 95-219. http://dx.doi.org/10.11575/PRISM/30271
The Idea of Progress in Modern Muslim Thought: The Views of ‘Abduh and Iqbal on Reason And Tradition
Kassam, Karim-Aly. 1998. “The Idea of Progress in Modern Muslim Thought: The Views of ‘Abduh and Iqbal on Reason And Tradition.” In Islamica, 2(4): 45-49.
Gender Analysis: Its Strengths and Weaknesses, and Requisite Skills for Effective Gender Planning
Kassam, Karim-Aly. (1997). Gender Analysis: Its Strengths and Weaknesses, and Requisite Skills for Effective Gender Planning. In Social Development Issues, 19(2/3): 189-202.
Development and the Changing Gender Roles of Gwich’in Women
Kassam, Karim-Aly and Wanda Wuttunee. (1997). Development and the Changing Gender Roles of Gwich’in Women. D. Poff and T. Fletcher (Eds.), Northern Futures. Selected Proceedings of the Conference of the Canadian Research Institute for the Advancement of Women. Prince George: University of Northern British Columbia. 52-69. http://dx.doi.org/10.11575/PRISM/30270
Integration of Islam in Young Ottoman Thought
Kassam, Karim-Aly. 1993-94. “Integration of Islam in Young Ottoman Thought.” Part I in Islamica, 1(3) August 1993: 10-14. Part II in Islamica, 1(4) January 1994: 15-21.