Scott, Paul; Duncan, Peter; Green, Jonathan A. (2015-01-02). "Food preference of the Black-headed Gull Chroicocephalus ridibundus differs along a rural–urban gradient". Bird Study. 62 (1): 56–63. doi:10.1080/00063657.2014.984655. ISSN0006-3657.
worldcat.org
Scott, Paul; Duncan, Peter; Green, Jonathan A. (2015-01-02). "Food preference of the Black-headed Gull Chroicocephalus ridibundus differs along a rural–urban gradient". Bird Study. 62 (1): 56–63. doi:10.1080/00063657.2014.984655. ISSN0006-3657.