Tretyakova M.I. , a.o. , Maslennikova N.V. , Chernyavsky M.M. , Anzon Z.V. , Chasnikov I.Y. , Shakhova C.I. Coherent production of particles by 60 GeV/c pions on emulsion nuclei. Phys.Lett.B , Vol.31B,N4 , с. P.241-245 , 01.1970