How to write in a book

One of the unsung side benefits of researching a nonfiction book is the stuff you learn that never makes it into the finished product. Reading one of C.S. Lewis' letters inspired me to revamp my note-taking, specifically the way I mark up books. I know some people regard writing in books as a sacrilege, but it's unavoidable in my profession. Much of the time the books are advance reader's copies (ARCs), unproofed printings for the convenience of journalists and booksellers and not "real...