Complex sentence: These include the two U.S. National Family Violence Surveys (Straus & Gelles, 1990), the National Violence Against Women Survey (Tjaden & Thoennes, 2000), this research has tended to show men and women equally violent.
Split into simpler sentences: These include the two U.S. National Family Violence Surveys (Straus & Gelles, 1990) and the National Violence Against Women Survey (Tjaden & Thoennes, 2000). This research has tended to show men and women equally violent.