C. A. Gordon, A. R. Hood, and J. R. Ellis, “Descriptions and revised key to the eggcases of the skates (Rajiformes: Rajidae) and catsharks (Carcharhiniformes: Scyliorhinidae) of the British Isles”, Zootaxa, vol. 4150, no. 3, pp. 255–280, Aug. 2016.