Evans, David A.; Rajapakse, Hemaka A.; Chiu, Anna; Stenkamp, Dirk Angewandte Chemie - International Edition, 2002, vol. 41, # 23 p. 4573 - 4576 doi: 10.1002/1521-3773(20021202)41:23<4573::AID-ANIE4573>3.0.CO;2-S