Esparza, B., A. Martínez-Abraín, S. Merino, och D. Oro. ”Immunocompetence and the Prevalence of Haematozoan Parasites in Two Long-Lived Seabirds”. Ornis Fennica, vol. 81, nr 1, mars 2004, s. 40–46, https://ornisfennica.journal.fi/article/view/133611.