Callahan, Joan R. Study guide to accompany Life : the science of biology by William K. Purves and Gordon H. Orians / [electronic resource] / prepared by Joan R. Callahan et al. for P.S. Associates, Inc.. — Sunderland, Mass. : Boston, Mass. : : Sinauer Associates ; : W. Grant Press,, c1983.. — 433 p. ; 28 cm.