A "strong backlist" refers to a collection of previously published books by an author or a publisher that continue to sell well even after some time has passed since their initial release. Full definition
In our opening - day collection, we made sure that there's a very strong backlist component to it.» (thedigitalshift.com)
Bloomsbury has an excellent track record in exploiting digital opportunities; this acquisition will enable us to develop Continuums 7,000 strong backlist through conversion to e-book formats and the creation of new subscription based academic services. (eoinpurcellsblog.com)
In fact, a strong backlist of books can help promote the sale of a new book and can increase book sales in general. (aer.io)