Saperas, N. & Chiva, M. & Pfeiffer, D.C. & Kasinsky, H.E. & Ausió, J. (1997)
Sperm nuclear basic proteins (SNBPs) of agnathans and chondrichthyans: variability and evolution of sperm proteins in fish. Journal of Molecular Evolution, 44(4), 422–431
DOI: 10.1007/PL00006162

Saperas, N. & Chiva, M. & Bols, N.C. & Kulak, D. & Kasinsky, H.E. (1993)
Sperm-Specific Basic Proteins in the Holocephalan Fish Hydrolagus colliei (Chondrichthyes, Chimaeriformes) and Comparison with Protamines from an Elasmobranch. Biological Bulletin, 185, 186–196