This could be either an HB or an HR in a circle.

A designer about whom little is known - she's mentioned as the designer for two different covers in two separate articles and publishers' announcements.

An unidentified designer who used a monogram that looks to be a larger S intersecting with a letter H. So far this monogram has only been found on covers of books published by the McLoughlin Brothers.

A rounded A on top intersecting with an F below it

Genjiro Yeto (1867-1924) was born Genjiro Kataoka in Arita, Japan. Late in life he reassumed the name Kataoka. He came to the United States around 1891 and studied at theNew York's Art Students League.

This does not seem the be the monogram used by either Amy Rand or Amy Richards. The designer who used this monogram did covers for Boston publishers Dana Estes, Little Brown, and L.C. Page and Company.

A monogram used by a designer that is speculated to be Alice Ball, the wife of Thomas Watson Ball.