A counterpane is generally thought of or used in reference to quilts. However, a counterpane is basically a decorative [usually cloth] bedspread cover.
The only book I know of that discusses knitted counterpanes is an OOP (out of print) book by Mary Walker Phillips titled Knitting Counterpanes: Traditional Coverlet Patterns for Contemporary Knitters. If you're lucky your local library might have a copy of the book or will be able to do an interlibrary loan with the book from another library. Sometimes you can find them on eBay; however, sometimes they can be expensive and other times they maybe reasonably priced. Also, you might checkout AbeBooks.com or Alibris but they can also get costly.