Complex sentence: The first three serial SO-152 were built by Uraltransmash in the end of 1970, in 1971-nine were produced and the works received the order for 70 SO-152 in 1973.
Split into simpler sentences: The first three serial SO-152s were built by Uraltransmash in the end of 1970, and in 1971 nine were produced. The works received an order for 70 SO-152 in 1973.