Thomson, Lila. "'Bu' As in 'Bun', Pu, Du, Tu, Fu, Yu, Gu, Ku, Hu, Ju, Lu" Baltimore Evening Sun, Box 1, Folder 5, Item 58, Robert L. Owen Collection, 1913-1946. https://fraser.stlouisfed.org/archival/5300/item/535445, accessed on January 19, 2026.