1. Barnes, C. D., and B. G. Katzung, Stimulus polarity and conditioning in planaria. Science, 1963, 141, 728.
2. Baxter, R., and H. D. Kimmel, Conditioning and extinction in the planarian. Am. J. Psych., 1963, 76, 665.
3. Bennett, E. L., and M. Calvin, Failure to train planarians reliably. Neurosci. Res. Program Bull. (M.I.T.), 1964, 2, 3.
4. Best, J. B., and E. Elshtain, Biophysics of unconditioned response elicitation in planarians by electric shock. Worm Runner’s Digest, 1966a, 8(1), 8.
5. Best, J. B., and E. Elshtain, Unconditioned response to electric shock: mechanism in planarians. Science, 1966b, 151, 7r7.