Before number 533, westerns published as part of this series did not include the 'Cleveland Western' logo, and were interspersed with non-westerns (mostly crime). After volume 600, all further volumes were westerns.
This series begins with volume 533. Volumes before that are included in the Cleveland Book series, which includes both crime and westerns. Gaps in this series between 533 and 600 are books in genres other than westerns; these books are includes in the Cleveland Book series.