Complex sentence: In the early 1967 the first in the USSR official UFO Study Group was formed, its first meeting held on May 17,1967 in the Moscow "ЦДАиК" (Aviation and Cosmonautics Center).
Split into simpler sentences: In the early 1967 the first official Soviet UFO Study Group was formed. Its first meeting was held on May 17,1967 in the Moscow "ЦДАиК" (Aviation and Cosmonautics Center).