@article{MZ_1973__134_171986,
     author = {Alexander Prestel and Richard Elman and Tsit-Yuen Lam},
     title = {On {Some} {Hasse} {Principles} over {Formally} {Real} {Fields.}},
     journal = {Mathematische Zeitschrift},
     pages = {291--302},
     publisher = {mathdoc},
     volume = {134},
     year = {1973},
     zbl = {0277.15013},
     url = {http://geodesic.mathdoc.fr/item/MZ_1973__134_171986/}
}