1. Hasen M. Maekawa & F.Kita, 1989. Studies of interspecific hybrids in the genus Melilotus from the plant breeding stand point, XIII. Studies of interspecific cross compatibility between M. officinalis and M. alba, and cytogenetics of the F1 hybrids obtained. Res. Bull. Univ. Farm Hokkaido Univ. 26: 53–63.
2. Kita F., 1977. Problems of sweetclover breeding through interspecific crosses. Recent Adv. Breed. 18: 117–128. (in Japanese)
3. Lang R.C. & H.J.Gorz, 1960. Factors affecting embryo development in crosses of Melilotus officinalis x M. alba. Agron. J. 52: 71–74.
4. Sano Y. & F.Kita, 1975. Cytological studies of several interspecific F1 hybrids in the subgenus Eumelilotus. J. Fac. Agr. Hokkaido Univ. 58: 225–246.
5. Sano Y. & F.Kita, 1978a. Reproductive barrers distributed in Melilotus species and their genetic bases. Can. J. Genet. Cytol. 20: 275–289.