==Selected bibliography==*"Results of Ornithological Explorations in the Commander Islands and in Kamtschatka" (1885)*" Birds of Kauai Island, Hawaiian Archipelago / collected by Mr. Valdemar Knudsen, with description of new species" (1887)*"Notes on a third collection of birds made in Kauai, Hawaiian Islands" (1890)*"The Poisonous Snakes of North America" (1895)*"The Russian Fur-Seal Islands" (1896)*"Herpetology of Porto Rico" (1904)*"Herpetology of Japan and Adjacent Territories" (1907)*"A new Gerrhonotine Lizard from Costa Rica" (1907)*"Three new species of lizards from the Philippine Islands" (1908)*"A new genus and species of lizard from Florida" (1911)*"A new Scincid Lizard from the Philippine Islands" (1911)*"Results of the Yale Peruvian Expedition of 1911.
* Results of Ornithological Explorations in the Commander Islands and in Kamtschatka (1885)* Birds of Kauai Island, Hawaiian Archipelago, collected by Mr. Valdemar Knudsen, with description of new species (1887)* Notes on a third collection of birds made in Kauai, Hawaiian Islands (1890)* The Poisonous Snakes of North America (1895)* The Russian Fur-Seal Islands (1896)* Herpetology of Porto Rico (1904)* Herpetology of Japan and Adjacent Territories (1907)* A new Gerrhonotine Lizard from Costa Rica (1907)* Three new species of lizards from the Philippine Islands (1908)* A new genus and species of lizard from Florida (1911)* A new Scincid Lizard from the Philippine Islands (1911)* Results of the Yale Peruvian Expedition of 1911.