Crawford, RJM, PS Sabarros, T Fairweather, LG Underhill, and AC Wolfaardt. 2008. “Implications for Seabirds off South Africa of a Long-Term Change in the Distribution of Sardine”. African Journal of Marine Science 30 (1):177-84. https://doi.org/10.2989/ajms.2008.30.1.18.468.