If you don't find anything, then widen your search to a broader subject area. You could broaden the search by looking for books on criminal sentencing or books on the war on drugs. Books on these topics are likely to discuss drug sentences. Like periodical articles, books are either popular or scholarly. To determine if a book is scholarly first check the publisher.
University presses publish most scholarly books.
Also, look for footnotes and a bibliography at the end of the book.