1. Sotavalta, O., Ann. Zool. Soc. ‘Vanamo’, 16, 8, 1 (1954).
2. Dotterweich, H., Zool. Jahrb., Abt. allg. Zool. Physiol., 44, 399 (1928). Krogh, A., and Zeuthen, E., J. Exp. Biol., 18, 1 (1941). Dorsett, D. A., J. Exp. Biol., 39, 579 (1962).
3. Richards, O. W., The Social Insects, 20 (Harper and Brothers, New York, 1961).
4. Church, N. S., J. Exp. Biol., 37, 1, 186 (1960).
5. Pringle, J. W. S., Insect Flight, 50 (Camb. Univ. Press, 1957).