@article{AFM_1982_7_2_a16,
     author = {Timo Ketonen and Kaisa Nyberg},
     title = {Twisted sums of nuclear {Fr\'echet} spaces},
     journal = {Annales Fennici Mathematici},
     pages = {323--335},
     publisher = {mathdoc},
     volume = {7},
     number = {2},
     year = {1982},
     doi = {10.5186/aasfm.1982.0720},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.5186/aasfm.1982.0720/}
}