When the subject-word is the same as the heading of the subject-entry this reference need not be made; but it will not do to omit an important title-entry when there are many titles under the subject-heading or they are much subdivided, so that it would be difficult to find the title-entry there. Thus an anonymous book, “France and the Pope,” would no doubt have a subject-entry under some subdivision of France, but as this in a large catalogue would be little help towards finding the book, it should also have a reference among the titles which follow the subject France. Of course if there were only a dozen titles under France one entry would be enough.
b. For other works, when the subject-word is not the same as the name of the subject selected by the cataloguer.
In this case, however, a cross-reference, which will answer for all titles, is to be preferred to a collection of subject-word references, being more economical and nearly as convenient to the inquirer. Suppose, for instance, that Insects is preferred as a subject-name to Entomology. It will be better and more sparing of space to say once for all “Entomology. See Insects,” referring a man to a part of the catalogue where he will find not only the book he seeks but many similar ones, than to make number of references like these:
Entomologie, Cours de. See Latreille, P. A.
Entomologique, Bibliographie. See Percheron, A.
Entomology, Dialogues on. See Dialogues.
Entomology, Elements of. See Dallas, W. S.; Ruschenberger, W. S. W.
Entomology, Introduction to. See Duncan, J.; Kirby, W.
which will serve his turn only for the particular book he has in mind, and serve it very little better than the general reference. {45}
89. Make title references (first-word, catch-word, or subject-word) for works which are entered under the names of societies or of governments.