@article{MZM_1986_39_3_a3,
     author = {V. F. Babenko and S. A. Pichugov},
     title = {An exact inequality for the derivative of a trigonometric polynomial having only real zeros},
     journal = {Matemati\v{c}eskie zametki},
     pages = {330--336},
     publisher = {mathdoc},
     volume = {39},
     number = {3},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1986_39_3_a3/}
}