Reference

Les G. Underhill, Philip A. Whittington, Robert J. M. Crawford, Anton C. Wolfaardt (1999/2000): Five years of monitoring African Penguins (Spheniscus demersus) after the ’"Apollo Sea" oil spill: a success story identified by flipper bands – Vogelwarte - Zeitschrift für Vogelkunde – 40_1999: 315 - 318.