@article{10_4064_sm_25_3_271_276,
     author = {J. Sch\"affer},
     title = {Another characterization of {Hilbert} spaces},
     journal = {Studia Mathematica},
     pages = {271--276},
     publisher = {mathdoc},
     volume = {25},
     number = {3},
     year = {1964},
     doi = {10.4064/sm-25-3-271-276},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-25-3-271-276/}
}