1. M. Shifman (Ed.): Handbook of QCD “At The Frontier of Particle Physics/Boris Ioffe Festschrift”, Vols. 1–3. World Scientific, Singapore, 2001, 2151 pp.
2. M. A. Shifman: in Continuous Advances in QCD. (Ed. A. Smilga), World Scientific, Singapore, 1994, p. 249, [hep-ph/9405246].
3. I. Bigi, B. Blok, M. A. Shifman and A. Vainshtein: Phys. Lett. B 323 (1994) 408, [hep-ph/9311339]. The ongoing debate on this issue, with sometimes conflicting arguments, is reflected e.g. in: M. Neubert: in Heavy Flavors II. (Eds. A. J. Buras and M. Lindner), World Scientific, Singapore, 1998, p. 239, [hep-ph/9702375]; N. Uraltsev: in Proc. International School of Physics “Enrico Fermi”, Heavy Flavor Physics: A Probe of Nature's Grand Design, Varenna, Italy, 1997. (Eds. Ikaros Bigi and L. Moroni), IOS Press, 1998, p. 329, [hep-ph/9804275].
4. M. Shifman: in Particles, Strings and Cosmology. (Eds. J. Bagger et al.), World Scientific, Singapore, 1996, p. 69, [hep-ph/9505289].
5. B. Chibisov, R. D. Dikeman, M. Shifman and N. Uraltsev: Int. J. Mod. Phys. A 12 (1997) 2075, [hep-ph/9605465].