1. Snodgrass, R. E., "Principles of Insect Morphology" (1935).
2. Miall, L. C., Nature, 53, 152 (1895).
3. Poyarkoff, E., Arch. Zool. Exp. Gen., 54, 221 (1914).
4. Imms, A. D., "A General Textbook of Entomology" (1934).
5. Keilin, D., Parasit., 16, 240 (1924).