Besides the economies in subordinate entries already referred to, it will be seen that the second author's name has "etc." substituted for it; as a well-recognised further economy that may be adopted without hesitation.
No other entries of any kind are needed for the dictionary catalogue, as the book is adequately catalogued as shown.
For the classified catalogue, the author-entry is marked 330.2 (300 Sociology, 330 Political Economy, 330.2 Compends), and the entries for the indexes are
Economics 330
Political Economy 330
Ely, R. T., &c. Elem. economics 330.2
The writers of a published correspondence are regarded as joint-authors in the same way, except that a book like
The correspondence of Thomas Carlyle and Ralph
Waldo Emerson, 1834-1872. 2 v. ports. 1883
cannot be covered very satisfactorily by an entry under the first-named and a reference under the second, as in the Ely-Wicker above, such a book needing two entries. An examination of it shows that the letters were edited by Charles Eliot Norton, and, though this is not stated on the title-page, it goes into the principal entry, but between brackets (not parentheses), which, as Cutter says in his Rules, are important, "both as a check on indiscriminate addition and as an aid to identification." The main-entry is
Carlyle, Thomas, and Ralph Waldo Emerson.
Correspondence, 1834-72; [ed. by Charles
Eliot Norton.] 2 v. ports. 1883
and the second entry under