Given a reference text about the Organization of the Petroleum Exporting Countries, when was OPEC founded and how do economists describe OPEC's power over oil markets?

The Organization of the Petroleum Exporting Countries (OPEC) was founded on September 14, 1960.  Economists describe OPEC as a cartel that limits free market competition by setting production quotas for its members. The impact of OPEC's supply quotas are most acute during times of war or civil disorder when crude oil supplies are already restricted. Cheating by member nations dilutes the power of OPEC over oil supply and prices.