Hill, Arthur William Sir (1875–1941) letter to Prain, David Sir (1857–1944), 10 November 1923, Box: 3, Folder: 36. William Winfield Ray collection of 20th century botanists correspondence and other materials, HIBDARC-0048. Hunt Institute for Botanical Documentation Archives. https://as.huntbot.org/repositories/2/archival_objects/4000 Accessed March 20, 2026.