00424nam a2200157Ia 4500008004100000020001500041082001600056100001900072245006000091260003500151300000800186650001800194650001800212653001200230653002400242170901s1979    xx            000 0 und d  a0123187508  a574.5bH14T  aHalfon, Efraim 0aTheoretical Systems EcologybAdvances and Caste Studies  aNew YorkbAcademic Pressc1979  a516  aLife sciences  aPure Sciences  aEcology  aMathematical models