J. R. Anderson, Response and risk assessment in rural ecosystems: from models and plots to define universes, Agric. Ecosyst. Environ, vol.82, pp.261-271, 2000.

J. P. Aubin, Viability theory, Birhaüser, Boston, 1991.

J. P. Aubin, Dynamic economic theory: a viability approach, Birhäuser, 1997.

F. Barth, Nomads of South Persia, 1961.

C. Béné, L. Doyen, and D. Gabay, A viability analysis for a bio-economic model, Ecol. Econ, vol.36, pp.385-396, 2001.

E. Bernus, Le contrôle du milieu naturel et du troupeau par les éleveurs touaregs sahéliens, pp.67-74, 1979.

N. Bonneuil and . Malthus, Boserup and population viability, Math. Popul. Stud, vol.5, pp.107-119, 1994.

P. Cardaliaguet, A differential game with two players and one target, SIAM J. Appl. Math, vol.34, pp.1141-1460, 1996.

T. H. Clutton-brock, S. D. Albon, and F. E. Guinness, Fitness cost of gestation and lactation in wild mammals, Nature, vol.337, pp.260-262, 1989.

S. Cournut, Le fonctionnement des systèmes biologiques pilotés : simulation à évènements discrets d'un troupeau ovin conduit en trois agnelages en deux ans, 2001.

L. Doyen and C. Béné, Sustainability of fisheries through marine reserves: a robust modelling approach, J. Environ. Manage, vol.69, pp.1-13, 2003.

L. Doyen and M. Tichit, A viability analysis of mixed herd management in uncertain climatic environments, Cahiers du Centre de Recherche Viabilité Jeux Contrôle, pp.1-25, 1999.

V. Ducrocq, Statistical analysis of length of productive life for dairy cow of the Normand breed, J. Dairy Sci, vol.77, pp.855-866, 1994.

V. Ducrocq, Survival analysis, a statistical tool for longevity data, Proceedings of the 48th Meeting of the European Association for Animal Production, pp.223-225, 1997.

D. Genin, H. Alzerreca, ;. Resena-de-la-vegetacion-de-la-zona-de-turco, and L. Paz, Un Sistema Pastoril Camélidos -Ovinos del Altiplano Arido Boliviano, Waira Pampa, pp.35-56, 1995.

D. Genin and M. Tichit, Degradability of Andean range forages in llamas and sheep, J. Range Manage, vol.50, pp.381-385, 1997.

D. Genin, Z. Villca, and P. Abasto, Diet selection and utilization by llamas and sheep in a high altitud-arid rangeland of Bolivia, J. Range Manage, vol.47, pp.245-248, 1994.

N. Girard and J. Lasseur, Stratégies d'élevage et maîtrise de la répartition temporelle de la production. Exemple des élevages ovins allaitants en montagne méditerranéenne, Cah. Agric, vol.6, pp.115-124, 1997.

F. Jacquet and J. Pluvinage, Climatic uncertainty and farm policy: a discret stochastic programming model for cereal-livestock farms in Algeria, Agric. Syst, vol.53, pp.387-407, 1997.

E. Landais, Recherche sur les systèmes d'élevage, Questions et perspectives, INRA SAD 87, 1987.

J. L. Lemoigne, La Théorie du Système Général. Théorie de la Modélisation, 1983.

R. Mace, Pastoralists herd composition in unpredictable environments: a comparison of model predictions and data from camel-keeping groups, Agric. Syst, vol.33, pp.1-11, 1990.

R. Mace, Nomadic pastoralists adopt subsistence strategies that maximize long-term household viability, Behav. Ecol. Sociobiol, vol.33, pp.329-334, 1993.

R. Mace and A. Houston, Pastoralists strategies for survival in unpredictable environments: a model of herd composition that maximizes household viability, Agric. Syst, vol.31, pp.185-204, 1989.

M. Mangel and C. Clark, Dynamic modeling in behavioral ecology, 1988.

E. J. Milner-gulland, R. Mace, and I. Scoones, A model of household decisions in dry-land agropastoral systems, Agric. Syst, vol.51, pp.407-430, 1996.

P. Morlon, B. Montoya, and S. Channer, Comprendre l'Agriculture Paysanne dans les Andes Centrales, pp.331-364, 1992.

C. H. Moulin, Performances animales et pratiques d'élevage en Afrique sahélienne. La diversité du fonctionnement des troupeaux de petits ruminants dans la communauté rurale de Ndiagne (Sénégal), 1993.

E. A. Roth, Traditional pastoral strategies in a modern world: an example from northern Kenya, Hum. Organ, vol.55, pp.219-223, 1996.

S. Sandford, Management of pastoral development in the third world, 1983.

I. Scoones, Range ecology at desequilibrium. New models of natural variability and pastoral adaptation in African Savannas, Overseas Development Institute, pp.62-76, 1993.

D. F. Sieff, The effects of wealth on livestock dynamics among the Datoga pastoralists of Tanzania, Agric. Syst, vol.59, pp.1-25, 1999.

T. L. Thurow and C. A. Taylor, Viewpoint: the role of drought in range management, J. Range Manage, vol.52, pp.413-419, 1999.

M. Tichit, association camélidés -ovins dans un système pastoral de l'altiplano désertique de Bolivie, Master of science, CIHEAM, 1993.

M. Tichit, Cheptels multi-espèces et stratégies d'élevage en milieu aride : analyse de viabilité des systèmes pastoraux camélidés -ovins sur les hauts plateaux boliviens, 1998.

M. Tichit and D. Genin, Factors affecting herd structure in a mixed camelid -sheep pastoral system in the arid puna of Bolivia, J. Arid Environ, vol.36, pp.167-180, 1997.

M. Upton, Livestock productivity assessment and modelling, Agric. Syst, vol.43, pp.459-472, 1993.

W. S. Mathematica and L. Livre, , 1997.