The British Library. An online search of the OPAC, pre-1976 Reference Collections located 126 Mosher books, and additional 7 post-1923 Mosher books, 32 separately listed titles from The Bibelot, a set of The Bibelot, and 3 books related to Mosher.
Newberry Library. There are about 170 Mosher books in the collection including some significant items in the Wing Collection (a copy of The Garland of Rachael with related manuscript material loosely inserted, Emilie B. Grigsby’s copy of Mimes on pure vellum, and a copy of Charles Van Cise Wheeler’s unpublished bibliography of Edward Fitzgerald’s translation of The Rubáiyát (Wheeler bought Mosher’s personal Rubáiyát collection).
New York Public Library. There are 214 Mosher entries in The New York Public Library Catalogue of Special & Private Presses in the Rare Book Division. Vol. II. (Boston, MA: G. K. Hall & Co., 1978). The library also has a folder of ephemera.
Temple University, Special Collections Department of the Samuel Paley Library. Temple University hosted the “Thomas Bird Mosher and the Art of the Book” Exhibit in 1992. In addition to around 100 Mosher books and catalogues found in the Richard W. Ellis Collection, there are numerous letters in the Gertrude Traubel (daughter of Horace Traubel) Collection which chronicle some of the relationships of the family with Mosher. Mosher is also one of the prominently mentioned individuals in the Gordon Bottomley/Constable & Co. papers.
University of British Columbia, Special Collections (The Norman Colbeck Collection). The number of Mosher’s books in this collection is well below the other institutions listed, but 26 Mosher books from collection are cited in the present bibliography. As a whole, the collection represents one of the finest assemblages of 19th Century publications, Edwardian poetry, and belles lettres which formed the backdrop for Mosher’s tastes and publishing efforts.
University of California – Berkeley, The Bancroft Library. In addition to some of the books from the Mosher Press, there are seven of Mosher’s books on pure vellum (five of which are bound by the Club Bindery) and two others Mosher books in outstanding bindings. These books were given to The Bancroft Library by Norman A. Strouse.
University of Texas at Austin, Harry Ransom Humanities Research Center Library. There are at least 290 Mosher books and related materials at the HRC, including 25 volumes from Mosher’s library. Some of the holdings are located in the Christopher Morley Collection, and some are in the Edward L. Tinker Collection.
University of Virginia, The Clifton Waller Barrett Collection includes run of original letters and inscribed copies from Robert Frost to Mosher from the original sale of Mosher’s library in 1948. Several of these letters appear in Lawrance Thompson’s Selected Letters of Robert Frost. (NY, 1964). Also, the papers of William Braithwaite include Mosher correspondence.