00246nam a2200097 a 450000500170000008200230001710000190004024500320005926000350009130000220012620251203090505.0  a574.50184,bD, hal  aHalfon, Efraim  aTheoretical systems ecology  aNew YorkbAcademic Pressc1979  axvi, 516p, 22 cm.