After 1900, a number of publishers did not or currently do not put the date on the title page of their first editions.
In the early 1900s, many publishers began to identify the first edition on the copyright page. A variety of statements have been used and continue to be used to denote a first edition, such as "First Edition," "First Printing," "First Impression," "First published (Year, or Month and Year)," or simply "Published (Year, or Month and Year)." A few publishers have placed or place their logo, colophon, or a code (generally "1" or "A") on the copyright page of the first edition. Publishers who did not or do not use a first-edition statement, in most cases, note subsequent printings on the copyright page.
If a book is collectible, a true first edition is usually more valuable than other editions in the same condition. As you can see from this article, determining whether a book is a first edition or not can be tricky. If you are planning on buying or selling collectible books, you will need to be able to accurately identify true first edition books.
