1. CLEO Collaboration, D.M. Asner et al., CLEO CONF 97-13; B. Behrens, CLEO Collaboration, talk presented at the conference on B Physics and CP violation Honolulu, Hawaii, March 1997; F. Würthwein, CLEO Collaboration, talk presented at the Recontres du Moriond, QCD and high energy hadronic interactions, Les Arcs, March 1997, hep-ph/9706010.
2. CLEO Collaboration, S. Anderson et al., CLEO CONF 97-22a, 1997.
3. I. Halperin, A. Zhitnitsky, hep-ph/9704412, hep-ph/975251, hep-ph/9706316; E.V. Shuryak, A. Zhitnitsky, hep-ph/9706316; D. Atwood, A. Soni, hep-ph/9704352; W.S. Hou, B. Tseng, hep-ph/9705304; A.L. Kagan, A. Petrov, hep-ph/9707354; C.S. Kim, D. London, T. Yoshikawa, work in progress.
4. M. Bauer, B. Stech, Phys. Lett. B 152 (1985) 380; M. Bauer, B. Stech, M. Wirbel, Z. Phys. C 34 (1987) 103.
5. G.P. Lepage, S.J. Brodsky, Phys. Rev. D 22 (1980) 2157; for recent extensive review, see A.J. Brodsky, H.-C Pauli, S.S. Pinsky, hep-ph/9705477.