Holt, E.W.L. (1894)
North Sea investigations (continued). Journal of the Marine Biological Association, (Ser. 2), 3, 169–201 and [1895]292–299
Leigh-Sharpe, W.H. (1922)
The comparative morphology of the secondary sexual characters of elasmobranch fishes. Memoir III, IV, V Journal of Morphology, 36, 191–243