@article{COMIM_1995_3_1_a7,
     author = {Tak\'acs, Jozef},
     title = {Positivity theorem},
     journal = {Communications in Mathematics},
     pages = {67--70},
     year = {1995},
     volume = {3},
     number = {1},
     mrnumber = {1474068},
     zbl = {0854.35084},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/COMIM_1995_3_1_a7/}
}