1. Andeweg, J. M., and A. Van Kooten: The practical importance of an identification of garden pea varieties in the seedling stage. Euphytica 6, 237–241 (1957). Meded. Inst. Vered. Tuinb. gew. Wageningen 120 (1958).
2. Braak, J. P., and L. Smeets: The phytotron of the Institute of Horticultural Plant Breeding at Wageningen, Netherlands. Euphytica 5, 205–217 (1956).
3. Morris, G. P.: Investigations into the use of the first two leaves of pea seedlings in varietal identification. Journal of the National Institute of Agr. Bot. 6, 489–493 (1953).
4. Peters, Nelson, Spanier: Contribucae á identificaçao de variedades de ervilha (Pisum sativum L.) pela morfologia dos catafilos. Jornada de Agrinomia do Rio Grande Do Sul. Dec. 1954.
5. Vaart, F. M. Van Der: The identification of pea varieties in the seedling stage. Euphytica 1, 29–33 (1952).