Box-folder 143:12

Scope and Contents From the Sub-Series: Contains notes, drafts and final versions of speeches and lectures given by Tombaugh at various events, as well as related correspondence, publicity, and background material. Papers read at professional meetings are filed in the Writings subseries. General correspondence, notes, and publicity is filed first, followed by lectures in chronological order. Lecture reference files containing background material are arranged alphabetically at the end.