We study in terms of corresponding Köthe matrices when every continuous linear operator between two Köthe spaces is bounded, the consequences of the existence of unbounded continuous linear operators, and related topics.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-sm152-1-2, author = {P. B. Djakov and M. S. Ramanujan}, title = {Bounded and unbounded operators between K\"othe spaces}, journal = {Studia Mathematica}, volume = {151}, year = {2002}, pages = {11-31}, zbl = {1037.46004}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm152-1-2} }
P. B. Djakov; M. S. Ramanujan. Bounded and unbounded operators between Köthe spaces. Studia Mathematica, Tome 151 (2002) pp. 11-31. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm152-1-2/