Felger, A. H. 1902. “A Plan for Recording in a Condensed Form the Life-History Notes of Birds.” The Auk 19(2): 189–95. doi:10.2307/4069312.

Felger, A. H. 1907. “A Card System of Note-Keeping.” The Auk 24(2): 200–205. doi:10.2307/4070853.

Ornithologist A. H. Felger describes the use and form of a custom card index system for creating a paper database of data for tracking and counting birds.

In particular he recommends it over prior uses of journaling methods. He suggests the ability to look at multiple cards in a row to be able to more easily extract usable data versus those older journaling methods.