Jack(2008) states that...
Jack(2008) demonstrates that...
Jack(2008) announces that...
Jack(2008) claims that...
Jack(2008) argues that...
Jack(2008) points out that...
The research from Jack(2008) shows that...
Jack(2008) states that...
Jack(2008) demonstrates that...
Jack(2008) announces that...
Jack(2008) claims that...
Jack(2008) argues that...
Jack(2008) points out that...
The research from Jack(2008) shows that...