@article{MZM_1968_3_3_a12,
     author = {E. K. Godunova and V. I. Levin},
     title = {A~general class of inequalities containing {Steffensen's} inequality},
     journal = {Matemati\v{c}eskie zametki},
     pages = {339--344},
     publisher = {mathdoc},
     volume = {3},
     number = {3},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1968_3_3_a12/}
}