Complex sentence: This was first conceptualized by Nikola Tesla in 1909 and Theodore Paraskevakos in 1971 and patented in 1974, and were offered for sale beginning in 1993.
Split into simpler sentences: This was first conceptualized by Nikola Tesla in 1909 and Theodore Paraskevakos in 1971, and patented in 1974. It was offered for sale beginning in 1993.