Johnson, L. J., Mill, P. J., Hull, S. L., & Ducrotoy, J. (2000). The occurrence of abnormal embryos in two ovoviviparous barnacle-dwelling littorinids. Journal of the Marine Biological Association of the UK, 80(3), (547-548). doi:10.1017/S0025315400002265. ISSN 0025-3154