This source has data for many species, and will be a major undertaking. Within each species account it often references an original source for diet data.
The Diet Database should be checked for the original source to make sure that we have not already incorporated those data.
Assuming not, the original source should be looked up, and data should be attributed to that original source in the Source field (rather than Schneider and Pence 1992).
When the original source is unavailable but sufficient diet data can be incorporated, list Schneider and Pence 1992 as the Source, but mention that the data originally come from the original source in the Notes field.
Schneider, K. J. and Pence, D. M. 1992. Migratory nongame birds of management concern in the Northeast.