March, 1949.]
TECHNIQUES OF EDITORIAL RESEARCH. 247 in itself. Neither Science Abstracts (13) nor Physikalische Berichte has "anything like complete coverage" (14) of physics and engineering articles.
The use of Chemical Abstracts will often help considerably in building up a bibliography on electrical engineering subjects. Nevertheless, out of the 750,000 scientific articles that appear annually in 15,000 periodicals, only one third are abstracted (iS). An additional search through the annual issues of The Engineering Index, The Industrial Arts Index, and through the Electronics Engineering Master Index will usually yield a largenumberof references. The Monthly Catalog of U. S. Government Publications may also indicate good sources of information.
A search for references is complicated by the differences in terminology encountered in the indexing and abstracting services, and different methods of classification present a problem to the searcher who attempts to locate the many sources of information. For example, reference material for this paper was found in the Engineering Index under the topic of "Engineering Writing," in the Industrial Arts Index under "Technical Writing," in the Readers' Guideto Periodical Literature