7Wood, Diana F . Problem based learning(Clinical review: ABC of learning and teaching in medicine) [J]. British Medical Journal, 2003,326(7348) : 328-330
8Amin,Carol EdD. A Comparison of Critical Thinking in Groups of Third-year Medical Students in Text, Video, and Virtual PBL Case Modalities[J]. Acad Med. 2003,78 : 204-211.