When Margot Rosenberg and Bern Marcowitz opened Dog Lovers Bookshop, they expected to be asked mostly about dogs and canine literature. But soon they found themselves fielding questions about the care of books. Customers who bought books, especially older volumes, on providing good care for their dogs were often eager for guidance on how to care for their cherished books, too. The book-care advice currently available is too often geared to book professionals,...