This fully annotated catalogue of nearly 5000 items from the library of the U.S. President, while unillustrated, is perhaps the finest and most detailed annotated bibliographical catalogue of the library of any scientist. It appears to be exhaustive in all details regarding each work in Jefferson's library. Sowerby was hired in 1942 by the Library of Congress to prepare a fully annotated catalogue of the books that Jefferson sold to the U.S. government in 1815. Because of the complexity of the task the first volume did not appear until 1952. Prior to the Jefferson project Sowerby had an extensive career as a rare book cataloguer:

After graduating from Girton College, Cambridge, Sowerby worked in London as a cataloger for rare book dealer Wilfrid Michael Voynich, and then briefly as a librarian at Birkbeck College before serving as a counterintelligence agent in Paris during World War I. Upon her return to England in 1916, Sowerby worked as a cataloger at Sotheby's, the first woman in the 'expert' workforce of an auction house. She moved to the United States in 1923, finding employment as a cataloger with the American Art Association and then at the New York Public Library (until January 1925).In March 1925, she became a bibliographer for A. S. W. Rosenbach in Philadelphia and New York City where she was employed until February 1942.

Reprinted by the University of Virginia Press with a new Foreward, 1983.