Gertrude Chandler Warner's most well known writing is "The Boxcar Children." But that series is far from the only professional writing Chandler did – she made a career as a writer while also teaching elementary school for decades. 

Research:

• Abate, M.A. Not Hoovervilles, But Hooch: Gertrude Chandler Warner’s The Boxcar Childrenand The Roaring Twenties. Child Lit Educ 47, 257–266 (2016). https://doi.org/10.1007/s10583-016-9275-5
• Braccidiferro, Gail. “The Boxcar Children: A Museum Caper.” New York Times. June 20, 2004. https://www.nytimes.com/2004/06/20/nyregion/the-boxcar-children-a-museum-caper.html
• Crowe, Chris. “Young Adult Literature: Rescuing Reluctant Readers.” The English Journal, vol. 88, no. 5, 1999, pp. 113–16. JSTOR, https://doi.org/10.2307/821799
• Ellsworth, Mary Ellen. “Gertrude Chandler Warner and the Boxcar Children.” Albert Whitman & Company. Morton Grove, Illinois. 1997.
• Lindberg, Mary Anne. “Survival Literature in Children’s Fiction.” Elementary English, vol. 51, no. 3, 1974, pp. 329–35. JSTOR, http://www.jstor.org/stable/41387166
• Meese, Ruth Lyn. “MODERN FAMILY: Adoption and Foster Care in Children’s Literature.” The Reading Teacher, vol. 66, no. 2, 2012, pp. 129–37. JSTOR, http://www.jstor.org/stable/23322722
• Tolentino, Jia. “’The Boxcar Children and the Spirit of Capitalism.” The New Yorker. June 2, 2016. https://www.newyorker.com/books/page-turner/the-boxcar-children-and-the-spirit-of-capitalism#:~:text=The%20second%20time%20that%20Gertrude,and%20family%20and%20life's%20rewards.
• Warner, Gertrude Chandler. “The Box-Car Children.” Rand McNally. Chicago/New York. 1924. Accessed online: https://www.gutenberg.org/files/42796/42796-h/42796-h.htm
• Warner, Gertrude Chandler. “Good Americans: First Lessons for the Littlest Ones.” Educational Publishing Company. Boston. New York. London. 1926. Accessed online: https://books.google.com/books?id=gONow7KFCB0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
• Warner, Gertrude Chandler. “The House of Delight.” Pilgrim Press. 1916. Accessed online: https://www.gutenberg.org/cache/epub/62714/pg62714-images.html
• Warner, Gertrude Chandler. “Star Stories for Little Folks.” Pilgrim Press. Boston, Chicago. 1918. Accessed online: https://archive.org/details/starstoriesforli00warn/page/8/mode/2up
• Warner, Frances and Gertrude. “Life’s Minor Collisions.” Houghton Mifflin. Boston and New York. 1921. Accessed online: https://archive.org/details/lifesminorcollis00warnrich/page/n9/mode/2up