@article{MZM_1990_48_1_a6,
     author = {T. Yu. Kuliev},
     title = {Filtered products, direct integrals, and convex analysis of numerical ranges},
     journal = {Matemati\v{c}eskie zametki},
     pages = {47--55},
     year = {1990},
     volume = {48},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1990_48_1_a6/}
}