This is a 2004 edition, but I believe that older editions can still be a useful place to start. This gives one names of publishers, informative articles, poetry contests, etc. Much of this may have changed in 20 years, but many publishers will still exist giving you a place to start. Then you can look up more current information on that publisher on the internet. I believe this enough that I'm keeping my 2005 edition for reference at this present time.

ISBN: 9781582971872