Complex sentence: On 1990-12-17, the station changed its call sign to WWEM, on 1995-04-03 to WSRI and on 1997-09-29 to the current WQSO.
Split into simpler sentences: On 1990-12-17, the station changed it's call sign to WWEM. On 1997-09-29 to the current WQSO.