Nollmeyer, Gustave E., Lynn Kelting-Gibson, and C. John Graves. “Mapping the Domain of Subject Area Integration: Elementary Educators’ Descriptions and Practices”. International Journal of Learning, Teaching and Educational Research 15, no. 9 (August 30, 2016): 1–27. Accessed May 26, 2026. https://ijlter.myres.net/index.php/ijlter/article/view/891.