Petzholdt's self-assurance carries him to the length of condemning books that he has not seen. Of a _Catalogo di commedie italiane_ published in 1776 he says: "It is said to be an extremely rare pamphlet that contains all the Italian comedies arranged in alphabetical order according to the authors' names. The rarity of the pamphlet seems to be greater than its bibliographical value."[163] As he indicates by an asterisk, he has not seen the _Catalogo_. Any complete or relatively complete account of Italian comedies is obviously a useful book. All that I have said in qualification of Petzholdt's merits does not diminish my admiration for him and his book. The _Bibliotheca bibliographica_ deserves a close and critical reading and only a great book survives such study. It is a masterpiece of modern bibliography. I turn now to a smaller book by another famous bibliographer. It is one of his minor efforts and will not detain us long. Joseph Sabin (1821-1881), a bibliographer of Americana, found John Power's little _Handy-Book about Books_ (London, 1870) very unsatisfactory. Although Power intended only to offer a brief selective list of books useful to a bibliographer or bibliophile, Sabin rejected it and wrote a much larger list. He entitled it _Bibliography of Bibliography, or a handy book about books which relate to books, being an alphabetical catalogue of the most important works descriptive of the literature of Great Britain and America, and more than a few relative to France and Germany_ (1877). It names perhaps twelve hundred titles and includes a few bibliographies printed as parts of non-bibliographical works and a few journal articles. The word "literature" in the title means publications in any field of learning and not merely belles lettres. Since Sabin provides neither a table of contents (his strictly alphabetical arrangement did not call for one) nor a subject index, one must read his book from cover to cover to find what it contains or to discover a particular subject bibliography. His occasional brief critical comments are often drawn from Petzholdt. As his subtitle indicates, he has included many books that are not bibliographies. Some he has carried over from Power's list that he has included in its entirety, although with misgivings, and some he has added on his own responsibility. Beloe's _Anecdotes of Literature and Scarce Books_ contains much bibliographical information, but can hardly be called a bibliography. Bonnardot's treatises on repairing bindings, Botford's and Clarke's books about libraries, and Constantin's treatise on library economy are books about books in the modern sense of the term. Like most writers of a bibliography of bibliographies, Sabin includes works dealing with the history of printing.