@article{INTM_1990_28_a1,
     author = {V. V. Vasil'ev and S. G. Krein and S. I. Piskarev},
     title = {Operator semigroups, cosine operator functions, and linear differential equations},
     journal = {Itogi nauki i tehniki. Seri\^a, Matemati\v{c}eskij analiz},
     pages = {87--202},
     year = {1990},
     volume = {28},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/INTM_1990_28_a1/}
}