The Martindale-Hubbell (R) Law Directory has been used as an authoritative resource for information on the worldwide legal profession from more than 130 years. The listing includes a database over one million law firms and lawyers in 160 countries. The Martindale-Hubbell Law Directory is accessible on CD-ROM, print-edition (26 volumes), and online at martindale.com, The Martindale-Hubbell directory includes law firms by practice area including Intellectual Property Law. Under the IP Law directory it is possible to search by US-State, Canadian Province, US Territories, and country.

References:
[1] Stim, R. "Intellectual Property. Patents, Trademarks, and Copyrights" West Legal Studies.
[2] Martindale-Hubbel Law Directory. www.martindale.com