p. 51 Wellcome Library M001440; Wellcome Collection CC BY 4.0.
p. 57 CALVIN AND HOBBES © 1993 Watterson. Reprinted with permission of ANDREWS MCMEEL SYNDICATION. All rights reserved.
p. 117 Courtesy of Dr. Jennifer Gunter.
p. 139 “Welche Thiere gleichen einander am meisten: Kaninchen und Ente,” Fliegende Bätter, October 23, 1892. University Library, Heidelberg.
p. 146 Reprinted with permission, ©1972 Dow Jones & Company, Inc. All rights reserved worldwide.