Q. When a person is referred to by first-name initials after the first mention, is it GP (or G.P., or G. P.)? The examples listed in CMOS only mention all initials (LBJ or JFK). Should there be periods? Should it be spaced or together? This is for a children’s book.

A. Chicago doesn’t address this situation, and even if we did, it wouldn’t be with little readers in mind, so you should work with the author and book designer to settle on a style that looks good in print and won’t confuse children.