found: Handbook of birds of the world, 1992:v. 3, p. 679 (extinct Great auk (Pinguinus impennis), the only recent flightless alcid; shared class affinities with the Razorbill so strong that it is sometimes included with the genus Alca.)
found: Sibley, C.G. Dist. & taxon. of birds of the world, 1990:p. 264 (Pinguinus impennis, Greak auk (last specimen 1844))
found: Bird families of the world, 1978:p. 113 (Garefowl or Great auk, Alca impennis, the large flightless species which became extinct in the 1840s)