Both editions of Great Books of the Western World include Additional Readings for each of the Great Ideas. In the first edition (1952) the works for each idea are divided into
- I. Works by authors represented in this collection. ...
- II. Works by authors not represented in this collection. ...
In the second edition (1990), list II is further divided chronologically into works from
- The Ancient World (to 500 A.D.)
- The Middle Ages to the Renaissance (to 1500)
- The Modern World (1500 and later)
For example, in the second edition, Time And Western Man (1927), by Wyndham Lewis, is included in the Additional Readings for the Great Idea of Time. Unfortunately, the Additional Bibliography for the set does not indicate the Great Ideas under which the works were listed. In this case, Time was the obvious place to look for it. It's possible it is listed under another idea, but it would likely be time-consuming to check.
Lewis's book is available free on-line at Internet Archive, with Notes including "This is a mirror of the Digital Library of India".