@article{RMC_2004_2004_1_a1,
     author = {D{\'\i}az-Barriga, J. Alejandro and Gonz\'alez-Acu\~na, Francisco and Marmolejo, Francisco and Rom\'an, Leopoldo},
     title = {Sumas activas {I.}},
     journal = {Revista matem\'atica complutense},
     pages = {287-319},
     publisher = {mathdoc},
     volume = {17},
     number = {2},
     year = {2004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RMC_2004_2004_1_a1/}
}