There are some good books you can buy but this is such a huge subject that the data of where the dump stations for RV'ers are in all parts of the U.S. is constantly being updated...Here's a good website with thousands of places you can go to clear those tanks...It's not complete..but it's pretty good
http://www.rvdumps.com/dumpstations/And here's another one...excellent listing...
Sanidumps at
http://sanidumps.com/John Clark and his wife Chris started this site from their home in Kelowna, BC..more than 17,000 dump stations in 13 countries