Breidbach, Olaf et al. Art Forms in Nature: The Prints of ERNST HAECKEL. 140 pp., with 100 color and 30 b&w illustrations. Large 4to, wraps. New York, Prestel, 1998.
Haeckel's prints, portraying microscopic organisms, plants and more highly developed creatures, were highly praised by scientists in his own day and have since influenced a variety of artists and designers, particularly Art Nouveau and the photography of Blossfeldt.

Breidbach, Olaf. Visions of Nature: The Art and Science of ERNST HAECKEL. 304 pp., nearly 300 illustrations, most in color. Large 4to, cloth. Munich, Berlin, London, New York, Prestel Publishing, 2006.
A renowned scientist and biologist, Haeckel's work was enormously influential in the art world, particularly the Art Nouveau and Surrealist movements. His acclaimed drawings of natural forms and objects are exquisitely detailed and rendered. This book, a richly illustrated profile, brings his theories and his art together in the most substantial treatment of his work to date.