The footnotes refer to these editions.
Ayn Rand, Philosophy: Who Needs It, Signet, Penguin Books, 1984
Ayn Rand, The Virtue of Selfishness, Signet, New American Library, 1964
Ayn Rand, For the New Intellectual, Signet, New American Library, 1961
Ayn Rand, Capitalism: the Unknown Ideal, Signet, New American Library, 1962
Ayn Rand, Introduction to Objectivist Epistemology, Mentor, New American Library, 1979
Ayn Rand, Atlas Shrugged, Signet, Penguin Group, 1957
S. I. Hayakawa, Language in Thought and Action, Harvest Edition, Harcourt, Brace & Company, 1992
There are also various links to on-line references in several posts.