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:

Peter Kropotkin's Mutual Aid, Part 1
45:03

SYMHC Classics: Haymarket Riot
37:40

Behind the Scenes Minis: Serving Lip and Ethics
26:19