106 books • 38 series
President Encyclopedia 1877-1889
President Encyclopedia 1809-1829
President Encyclopedia 1829-1849
President Encyclopedia 1889-1909
President Encyclopedia 1861-1877
President Encyclopedia 1849-1861
President Encyclopedia 1909-1929
President Encyclopedia 2001-2008
Los Animales (Animal Life) (Reference - Spanish - Science)
Science Encyclopedia Animal Life