IL SISTEMA DI C - Enciclopedia Cattolica, Vol. III, p. 1039

Machine translation of the 1948–1954 Italian original. The original text is authoritative.

THE C. B. SYSTEM OF THE LIBRARY OF CONGRESS. — Introduced by the Library of Congress in Washington, which has been publishing its outline, still incomplete, since 1904. It consists of various classes, marked by one or two letters of the alphabet, as follows:
A. General works. Polygraphy;
B. Philosophy and Religion (BA–BI. Philosophy; BJ–BZ. Religion);
C. Auxiliary disciplines of history;
D. History and Topography (excluding America);
E. General history and topography of America and the United States;
F. Local history and topography of America and the United States;
G. Geography and Anthropology;
H. Social Sciences and Economics;
I. Political Science;
K. Law;
L. Education;
M. Music;
N. Fine Arts;
P. Language and Literature;
Q. Science (excluding medicine);
R. Medicine;
S. Agriculture and agricultural industries;
T. Technology;
U. Military Science;
V. Naval Science;
Z. Bibliography and Library Science.

Each class is further subdivided by the addition of another letter (e.g., G. Geography; GA. Economic Geography) and a geographical designation using Arabic numerals, which, however, vary from class to class. Various other combinations of letters and numbers are used to indicate the author’s name, the title of the work, etc. (e.g., the work by M. Rosi, *L’Italia odierna*, is classified as follows: DG. 552. R. 779; D. History, DG. History of Italy; DG. 552, History of Italy, Risorgimento; R. 779 is the designation for the author Rosi). The Library of Congress publishes detailed indexes for each class and also prints the cards of the books it holds, supplying them, upon request, to other libraries; the richness of the information they contain allows them to be used as bibliographical repertories. In some libraries, such as the Vatican Library, these cards are merged with those of the alphabetical catalog into a single dictionary catalog.

The notation for authors. — In order to distinguish and arrange alphabetically two or more books by different authors on the same subject, notations have been devised that, when added to the symbol of the Dewey Decimal Classification or the Library of Congress system, serve to identify the author or at least the first letters of his name. They consist of the initial letter of the surname, followed by one or more Arabic numerals representing the subsequent letters; the resulting group is appended to the classification symbol, separated by a period. Special tables exist for these notations, the most widely used being the Cutter-Sanborn *Three-Figure Tables*.

BIBL.: On classification systems in general cf. E. C. Richardson, *Classification: Theoretical and Practical*, New York 1912; W. W. Bishop, *Practical Handbook of Modern Library Cataloguing*, Baltimore 1924; W. C. Berwick Sayers, *A Manual of Classifications for Librarians and Bibliographers*, London 1926; J. H. Quinn, *Library Cataloguing*, 1913. On Brunet’s system cf. G. Ottino–G. Fumagalli, *Bibliografia*, Milan 1916, pp. 245–58 (in the latest ed., 1935, this discussion was omitted; instead, pp. 310–11 contain a mention of Crozet’s system). For the Dewey Decimal Classification, in addition to M. Dewey’s *Decimal Classification and Relative Index*, 14th ed., New York 1942, cf. the same author’s *Abridged Decimal Classification and Relative Index for Libraries and Personal Use*, 4th ed., 1919; and the publication of the Institut International de Bibliographie, *Classification Décimale Universelle*, Brussels 1927–33; also useful is the pamphlet by the Biblioteca Apostolica Vaticana, *Sistemi di classificazione degli stampati*, 2nd ed., Vatican City 1941. For the Library of Congress classification system cf. *Library of Congress, Classification*, Washington 1904 ff., of which 24 volumes have appeared to date, and the aforementioned pamphlet from the Vatican Library. Alessandro Pratesi