"Hardcover bestsellers" refers to popular books that are published in a hardbound format. These books are usually the ones that sell the most copies and are often found on lists ranking the top-selling books. Full definition
I think most of you reading this know that the publishing industry makes most of its money through hardcover bestsellers. (leadpushers.com)
Turn of Mind, a literary page - turner about a retired orthopedic surgeon suffering from dementia and accused of killing her best friend, was a New York Times hardcover bestseller and named a Best Book of the Year by Newsday, Chicago Tribune, The Washington Post, The Guardian, and Kirkus Reviews. (bookbrowse.com)
Gone are the big sales realized in the known business cycle, where publishers could depend on the success of hardcover bestsellers and later make the same titles available in paperback, bringing in another chunk of change. (americanlibrariesmagazine.org)