Prefa is the form of Preference played in Greece. As in all forms of this game, a 32-card pack is used and there are three active players. Greek Prefa resembles Russian Preference, rather than the versions played in other parts of Eastern Europe, in that the bidder can contract for more than 6 tricks.
Rules and tactics of Prefa can be found on Eric Ball's Prefa page.
Thanos has published a free Prefa program for Windows.