@article{JRAM_1967__225_150780,
     author = {Harold Ruben},
     title = {Variance bounds and orthogonal expansions in {Hilbert} space with an application to inequalities for gamma functions and ...},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {147--153},
     publisher = {mathdoc},
     volume = {225},
     year = {1967},
     zbl = {0147.38105},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1967__225_150780/}
}