Why don't you have "The Green Ripper" or other John DMcDonald Travis McGee books?
We do have a few books by John D. MacDonald--see them here. As for The Green Ripper--older books eventually wear out and are generally not replaced, since by then they are out of print and not available through the library's regular suppliers. However, you could request this book through interlibrary loan (we would borrow it for you from another library system somewhere in the US; you would merely pay the postage for returning the item to the lending library); details on doing this can be seen here.
Let me know if you have any questions about this!