Gabbiano reale nordico (Larus argentatus)
Caption: Brehm, Alfred Edmund; Pechuel-Loesche, Eduard; Haake, Wilhelm Brehms Tierleben. Allgemeine Kunde des Tierreichs. Vögel - Dritter Band. (1892) - Permission granted to use under GFDL by Kurt Stueber. Source: www.biolib.de - Permission is granted to copy, distribute and/or modify this image under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.

Gabbiano reale nordico (Larus argentatus)
Caption: Picture modified from Anton Fritsch - Evropské ptactva (Europas Vögel), Tafelband (1871) - Permission granted to use under GFDL by Kurt Stueber. Source: www.biolib.de - Permission is granted to copy, distribute and/or modify this image under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

Gabbiano tridattilo (Rissa tridactyla)
Caption: Picture modified from Anton Fritsch - Evropské ptactva (Europas Vögel), Tafelband (1871) - Permission granted to use under GFDL by Kurt Stueber. Source: www.biolib.de - Permission is granted to copy, distribute and/or modify this image under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".