Biochemistry and physiology of visual pigments :  symposium held at Institut Fur Tierphysiologie, Ruhr-University Bochum/W. Germany, August 27-30, 1972 
edited by Helmut Langer. 
 - xiii, 363 pages :  illustrations ;  25 cm. 
<br/><br/><label>ISBN: </label>0387062041