How Do I Add Author Names In IBooks?

I’ve got an iBook Pro laptop running OS X (10.11.6) and iBooks version 1.5.
When I import a book to iBooks, often it shows the Author as “Unknown”, or else gives wrong information (e.g.: author listed as “FirstName LastName” rather than “LastName, FirstName”, so the Alphabetical By Author sorting sorts by FIRST rather than LAST name). It’s exceedingly irritating to have half an author’s books sorted by FirstName and the rest by LastName!
NONE of the advice I’ve found anywhere (including here) gives WORKING info on how to fix this. I’ve tried saving files as PDFs and changing/adding Author info when saving the PDF, but iBooks doesn’t show those changes.
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AmyCat