The reduced entry for our book accordingly becomes
Bell, Aubrey F. G.
In Portugal. 1912
Having the author or principal entry complete, we now proceed to examine the book for subject-entry, and find that it consists of descriptions of journeys to places off the beaten track in Portugal. Even with the title of the book so obvious and the subject so clearly named in it, it is wise not to take it for granted, and examine the book as it may contain something of value belonging to another subject—for example, there is a book of travel in the Near East bearing the title "Pen and pencil in Asia Minor" which contains no less than thirteen chapters upon silkworms and the silk industry, not only in the Levant, but in France and elsewhere—quite a respectable book within a book, but this the title-page fails to reveal. The subject of our book, however, is open to no doubt, and for the dictionary catalogue the subject-entry is
Portugal:
Bell, A. F. G. In Portugal. 1912
No further entries are called for than these two (author and subject).
In all entries subordinate to the main entry, where the fullest particulars concerning the book are given, the information is condensed sufficiently to identify the book upon the supposition that those who require more details will turn to the main entry for them. The omissions from the subordinate entries are the full Christian names of authors (initials alone being given), the names of editors, translators, or illustrators, the names of series, the collations, sizes, and places of publication. The entries used throughout this work demonstrate this. The dates of publications are invariably given in all entries except where shown.
It has been contended that all details are as much wanted under the subject as under the author. There is much to be said in favour of this, but it is impossible to make every entry a main-entry when expense and the size of the catalogue have to be considered.
When the time comes for preparing the manuscript of the catalogue for the press, should it happen that there was no other book upon the subject, then the form of entry can be changed to what may be called a subject-title-entry, thus
Portugal, In. Bell, A. F. G. 1912