@incollection{AST_1980__75-76__239_0, author = {Willems, Jan C.}, title = {Almost $A(mod \beta)-$ invariant subspaces}, booktitle = {Analyse des syst\`emes}, author = {Collectif}, series = {Ast\'erisque}, publisher = {Soci\'et\'e math\'ematique de France}, number = {75-76}, year = {1980}, zbl = {0459.93029}, mrnumber = {581719}, language = {en}, url = {http://archive.numdam.org/item/AST_1980__75-76__239_0/} }