M. A. Shifman, Talk at the Workshop Continuous Advances in QCD, p.9405246

M. A. Shifman, Quark?hadron duality, hep-ph/0009131

J. D. Bjorken, Invited talk at Les Rencontres de Physique de la Vallée d'Aoste, Phys. Rev. D, vol.43, issue.819, 1990.

I. Bigi, M. Shifman, N. Uraltsev, and A. Vainshtein, Heavy flavor decays, OPE, and duality in the two-dimensional ???t Hooft model, Physical Review D, vol.59, issue.5, p.54011, 1999.
DOI : 10.1103/PhysRevD.59.054011