Radiometric Performance of the SMOS Reference Radiometers - Assessment After One Year of Operation. - Juha Kainulainen; Andreas Colliander; Josep Closa; Manuel Martín-Neira; Roger Oliva; Guillermo Buenadicha; Pilar Rubiales Alcaine; Anssi Hakkarainen; Martti T. Hallikainen (IEEE Trans. Geosci. Remote. Sens., 2012)