Willoughby, E. E. (1947). Fifty printers' marks. Book Arts Club, University of California.
Cita Chicago Style (17a ed.)Willoughby, Edwin Eliott. Fifty Printers' Marks. Berkeley: Book Arts Club, University of California, 1947.
Cita MLA (9a ed.)Willoughby, Edwin Eliott. Fifty Printers' Marks. Book Arts Club, University of California, 1947.
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