6.—Make sure that the popular term has the same meaning as the scientific, and is as comprehensive.
7.—Avoid scattering books upon a single subject, though viewed from different standpoints, under several headings, if they can be concentrated under one heading.
8.—Avoid entries under first or other word of the title as far as possible, where a subject-entry is all that is needed. Title-entries should be the exception not the rule.
9.—Make a subject-heading when there are two or more books upon the same subject; when only one gives a subject title-entry.
10.—Series entries are to be given as such and not as a makeshift form of subject-entry.
11.—Form entries, generally speaking, are out of place in the dictionary catalogue. If given they are better relegated to an appendix.
12.—References and cross-references should be always subordinate and connected.
13.—References are rarely given from lesser to greater subjects, but should not be overlooked from greater to lesser.
14.—In no case should references be given from author to subject or vice versa, or in any form not distinctly relative, otherwise they are apt to be incongruous.
15.—Volumes of a collective or miscellaneous character require that each item be considered and catalogued as if a separate work.