Have you ever considered making a hard copy of your book?
The answer is no. Couple of reasons - the demand for a hard copy version is quite low - only a few people have asked, and a hard-copy version can get expensive especially when considering the different editions. The electronic format is convenient; it easily supports new editions; it allows a drop-down table of contents to be displayed to jump to any Chapter, and the document is cross-linked to jump to any reference; the PDF version has an easy search function, and in PDF, alt-back arrow allow you to return to wherever you were.

