This thick reference book is published annually by F&W Publications. It contains a mix of market listings (recent editions contain 1,700 to 1,800 markets) and articles that purport to give poets an insider's view of the poetry market and give them the information they need to introduce their work to the right editor.
Specific listed markets include mass circulation and literary magazines, trade book publishers, small presses and university quarterlies, along with information about current editors and editorial policy. It also includes indexes such as a chapbook publishers index, a geographical index, a subject index, etc.
I personally find this book to be useful, but be forewarned that the information in their listings may be stale due to the volatile nature of the publishing industry. Magazines are launched and fail every month, publishers change addresses and policies.
The best use of this book is to identify likely publishers, then do a web search to corroborate the information. Also, because buying one of these books each year is pretty expensive for most poets, I suggest seeking out a copy at your local library instead of buying one new.