@article{PA_2017_6_1_a4,
     author = {E. Neuman},
     title = {Wilker and {Huygens-type} inequalities involving {Gudermannian} and the inverse {Gudermannian} functions},
     journal = {Problemy analiza},
     pages = {46--57},
     publisher = {mathdoc},
     volume = {6},
     number = {1},
     year = {2017},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PA_2017_6_1_a4/}
}