Wallraff, Hans Georg Verhaltensphysiologie, Seewiesen, Max Planck Institut für Ornithologie, Max Planck Society;
Wallraff, H. G., Chappel, J., & Guilford, T. (1999). The roles of the sun and the landscape in pigeon homing. The Journal of Experimental Biology, 202(16), 2121-2126.