Wang W, Ma Z
Department of Mathematics, Southwest Normal University, Chongquing, People's Republic of China.
Math Biosci. 1994 Aug;122(2):235-48. doi: 10.1016/0025-5564(94)90060-4.
Studies of several population-toxicant models are discussed. Under the hypothesis that the exogenous input of toxicant into the environment is periodic in time, the conditions for permanence of populations are obtained.
