Complex sentence: In 1968, a branch of the Skochinsky Institute of Mining was established in Kohtla-Järve, and in 1984 the scientific-technical journal Oil Shale was founded in Estonia.
Split into simpler sentences: In 1968, the branch of Skochinsky Institute of Mining was established in Kohtla-Järve. In 1984, the scientific-technical journal Oil Shale was founded in Estonia.