1. Berry R.J. 1977. Inheritance and Natural History. William Collins Sons & Co Ltd. London. 350 pp.
2. Berry A.J. & Willmer P.G. 1986. Temperature and the colour polymorphism of Philaenus spumarius (Homoptera: Aphrophoridae). Ecol. Entomol. 11: 251–259.
3. Boucelham M. & Raatikainen M. 1984. The colour polymorphism of Philaenus spumarius (L.) (Homoptera, Cercopidae) in different habitats Ann. Entomol. Fenn. 50: 43–46.
4. Boucelham M. & Raatikainen M. 1987. The effect of altitude, habitat and geographical location on the polymorphism of Philaenus spumarius (L.) (Hom. Cercopidae). Ann. Entomol. Fenn. 53: 80–86.
5. Boucelham M., Hokkanen H. & Raatikainen M. 1988. Polymorphism of Philaenus spumarius (L.) (Homoptera, Cercopidae) in different latitudes, altitudes and habitats in the U.S.A. Ann. Entomol. Fenn. 54: 49–54.