00282nam a2200109 a 450000500170000002000150001708200180003210000200005024500370007026000430010730000220015020251203090500.0  a071021152X  a156.315,bwal  aWalker, Stephen  aAnimal learning: an introduction  aNew York: Routledge & Kegan Paulc1987  axiv,426p.c22 cm.