@article{JTNB_2009__21_3_703_0, author = {Jouni Parkkonen and Fr\'ed\'eric Paulin}, title = {On the closedness of approximation spectra}, journal = {Journal de th\'eorie des nombres de Bordeaux}, pages = {703--712}, publisher = {Universit\'e Bordeaux 1}, volume = {21}, number = {3}, year = {2009}, doi = {10.5802/jtnb.696}, zbl = {1205.11083}, mrnumber = {2605541}, language = {en}, url = {https://jtnb.centre-mersenne.org/articles/10.5802/jtnb.696/} }