by Shipley, Robert E., Powell, Carroll E., Harley, R. J.
Published in The journal of psychology (01.05.1970)

by Yen, T T, Pearson, D V, Powell, C E, Kirschner, G L
Published in Life sciences (1973) (01.01.1978)

by CARROLL E. POWELL, CLINTON L. CARTER
Year of Publication 30.05.1972