There are several directories that contain lists of production services compani es including special effects houses. A directory that happens to be close to h and is THE PRODUCER'S MASTERGUIDE (Shmuel [sic] Bension). I have the 1988 edit ion; there may be later ones, I know there were earlier editions. This particu lar directory is worth knowing about since it includes a wide range of informat ion that one should know (or know about) such as union and guild contract terms , film commissions in various jurisdictions, and a useful summary of the business of feature film production.