HarperCollins

• Harper & Brothers marked first editions with the words "First Edition" on the copyright page, a custom the firm confirmed in 1947.
• From 1912 Harper & Brothers also printed a two-letter code on the copyright page, one letter for the month and one for the year of printing (M stands for 1912).
• Where a printing line appears on the copyright page, the lowest number shows the printing, whatever order the numbers run in; a line with a 1 normally indicates a first printing.
• Book club editions are a common trap: their jackets usually carry no price on the front flap, so a priced jacket is one of the first things to check.

Harper (Harper & Brothers, then Harper & Row, then HarperCollins) marks first printings "First Edition" on the copyright page and also prints a code for the printing: two key letters for month and year from 1912, and a number line from about 1975.

By period

• Before 1912 a Harper & Brothers first edition carries the same single date on the title page and the copyright page.
• From 1912 Harper & Brothers printed two key letters on the copyright page giving the month and year the book was printed.
• The "First Edition" statement followed later. Two guides date it to 1922; the firm itself said in 1947 only that it began some years after the letters, so books from about 1912 to 1920 can have the letters without the statement.
• From about 1975 Harper & Row printed a number line on the copyright page, and HarperCollins books carry both "First Edition" and a number line. The lowest number left in the line is the printing, whatever order the numbers run in.

Reading the letter code

• The first letter is the month: A January, B February, C March, D April, E May, F June, G July, H August, I September, K October, L November, M December. There is no J.
• The second letter is the year: M for 1912, N 1913, O 1914 and so on to Z for 1925, again without J. The alphabet then restarts with A for 1926, so S can mean 1918 or 1943. The copyright date tells you which.
• A year letter well after the copyright date points to a later printing.

Traps

• Book club copies. A club jacket usually has no price on the front flap. Many club copies are smaller than the trade edition, but Book-of-the-Month Club copies are usually the same size and quality, so size alone is no guide: look also for a small blind stamp (a dot, circle or square) low on the rear board. BOMC printed prices on some jackets in the 1970s, but those copies still carry the stamp.

Example

• A Harper & Brothers copyright page with the letters "D-W" was printed in April 1922 (D for April, W for 1922); the same title with a year letter later than its copyright date is a reprint.