References
- Frye , B. E. 1967 . Hormonal Control in Vertebrates , New York : Macmillan .
- Ramsay , J. A. 1968 . Physiological Approach to the Lower Animals , 60 – 68 . London : Oxford .
- Siegal , S. 1956 . Nonparametric Statistics for the Behavioral Sciences , 116 – 127 . New York : McGraw-Hill .