Evaluation of Factors Affecting the Larval Density of Fejervarya kawamurai in Japanese Paddy Fields, Especially Focusing on the Existence of Other Anuran Larvae Noha, Kihiro and Shimada, Tomohiko, Current Herpetology, 36, 87-97 (2017), DOI:http://dx.doi.org/10.5358/hsj.36.87