ISHIYAMA, R. (1952)
Studies on the rays and skates belonging to the family Rajidae, found in Japan and adjacent regions. 4. A revision of three genera of Japanese rajids with descriptions of one new genus and four new species mostly occured in northern Japan. Journal of the Shimonoseki College of Fisheries, 2 (2): 1–34, Pls. 1–4.
ISHIYAMA, R. (1958)
Observations on the egg-capsules of skates of the family Rajidae, found in Japan and its adjacent waters. Bulletin of the Museum of Comparative Zoology at Harvard College, 118 (1): 1–24