@article{CMH_1973__48_139553,
     author = {Manfred Knebusch},
     title = {On the {Extension} of {Real} {Places}},
     journal = {Commentarii mathematici Helvetici},
     pages = {354--369},
     year = {1973},
     volume = {48},
     zbl = {0278.12106},
     url = {http://geodesic.mathdoc.fr/item/CMH_1973__48_139553/}
}