1. Allen, J. A.: The influence of physical conditions in the genesis of species. Ann. Rep. Smithsonian Inst. 1905, 375?402 (1906).
2. Bacq, Z. M.: Sur l'existence d'un rythme nycthéméral de metabolisme chez le coq. Ann. de Physiol. 5, 497?511 (1929).
3. Baldwin, S. P., and S. C. Kendeigh: Variations in the weights of the birds. Auk (Lancaster, Pa.) 55, 416?467 (1938).
4. Benedict, F. G.: Basal metabolism. J. of Biol. Chem. 20, 263?299 (1915).
5. ?: Vital energetics. Sex differences in respiration. Carnegie Inst., Wash., Publ. 503, 1?215 (1938).