No reference should be made to a title which does not indicate the information sought for. Thus, if a work contains an account of some subject which is not specified on the title, this must not be referred to unless a note is added to the title to show that the book does contain this information. Sometimes one reference will be sufficient for a group of titles. Thus, in referring from one form of an author's name to another, it is not necessary to repeat the titles under that author's name even in the shortest manner.
It is not well in subject references included in an alphabetical catalogue or in an alphabetical index of subjects to classify at all. Thus Gold should be under G, and Silver under S; and at the end of the heading of Metals or Metallurgy such cross-references as these can be added: "See also Gold, Silver."
It is not easy to calculate the average number of references to a given number of chief entries. If we exclude subject references, it may be roughly put at about a third. If subject references are included, it will be about two to one, or twice as many references as titles. Many titles will only require one reference, but others will help to turn the balance,—as, for instance, the following, which will require ten references:—
The Life of Haydn, in a Series of Letters written at Vienna [originally written in Italian by G. Carpani], followed by the Life of Mozart [by A. H. F. von Slichtegroll], with Observations on Metastasio, and on the Present State of Music in France and Italy. Translated from the French of L. A. C. Bombet, with Notes by the Author of the Sacred Melodies [W. Gardiner]. London, 1817. 8vo.
In the first place, Bombet is a pseudonym for Henri Beyle; therefore, according to the rule adopted in the catalogue, there must be a different reference. If the title is placed under Beyle, then there must be a reference from Bombet; and if under the pseudonym, there must be a reference from Beyle. There must be references from Haydn, Mozart, and Metastasio, from Slichtegroll, Carpani, and Gardiner, from Music, and possibly from France and Italy.
The specimen page here given will show how a subject index may be incorporated in one alphabet with an author's catalogue:—
| Case. | Shelf. | Size. | Date. | |
|---|---|---|---|---|
| II | 2 | Shuttleworth (Philip N.) The Consistency of the whole scheme of Revelation with itself and with Human Reason. London. | 12° | 1832 |
| LL | 3 | —Paraphrastic Translation of the Apostolical Epistles, with Notes. London. | 8° | 1840 |
| Siberia Travels: Dobell (1830) | ||||
| Sicily Travels, etc.: Brydone (1790), Hoare (1819), Swinburne (1783), Smyth (1824) | ||||
| — Volcanoes of: Hamilton (1772) | ||||
| — Vestiges of Ancient Manners: Blunt (1823) | ||||
| Sidmouth (Viscount) Life: Pellew (1847) |