Maybe Bombers , or Seaplanes would be more to the point of what you need. Everything listed under NT is a valid subject heading. In other words, check under these headings for more material similar to your topic. The same is true of SA or see also . These begin with a long dash and are also in bold.
Subdivisions break down a subject into specific parts.
Subdivisions are also handy for finding certain types of books. You would follow your subject with a subdivision for those types of materials. You could find statistics, or a subject limited to a certain geographical area by using subdivisions. Now that you know what words you want to use, you are ready to search. You will then get a screen where there are two columns.