I have read your FAQ page...and I don't see the letters you are talking about on my books...but I know they are old.
The first is "QuickDraw McGraw", the cost was 25 cents. On the inside it says "This is a Brand New Book" and the copyright says 1960. It is in very good condition.
The second is "How To Tell Time", the cost was 29 cents. On the inside it says copyright was 1957. It also is in very good condition.
I know you state our opinions may vary on the condition, but they have been shelved since my children no longer used them.
Can you please tell me what they might be worth.