 According to a  study done by Kopel Arkowitz(1974), Kopel, S. A., & Arkowitz, H. S. (1974).
<meaning-changed>  According to a  study done by Kopel Arkowitz(1974), Kopel, S. A., & Arkowitz, H. S. (1974).
 According to a 1974 study done by Kopel Arkowitz(1974), Kopel, S. A., & Arkowitz, H. S. (1974).