@article{10_4064_ap_4_2_201_213,
     author = {Andrzej Schinzel and Y. Wang},
     title = {A note on some properties of the functions \ensuremath{\varphi} (n), \ensuremath{\sigma}(n) and \ensuremath{\theta}(n)},
     journal = {Annales Polonici Mathematici},
     pages = {201--213},
     publisher = {mathdoc},
     volume = {4},
     number = {2},
     year = {1957},
     doi = {10.4064/ap-4-2-201-213},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-4-2-201-213/}
}