In the 1990s, various companies were established to research subjects and provide practice tests to teams. Two of the major ones were Acalon Cards and Exams and DemiDec, formed by former coach Dan Spetner and former Decathlete Daniel Berdichevsky, respectively. The two offer exams and study guides that can augment or replace USAD's official materials. USAD explicitly discouraged teams from ordering materials from third-party companies in the late 1998, though it later removed their discouragement from the curriculum page. USAD republished their discouragement just a few weeks after removing it, but did not publish such a warning in 2002.