@article{TUW-110103, author = {Hlawatsch, Franz}, title = {Regularity and unitarity of bilinear time-frequency signal representations}, journal = {IEEE Transactions on Information Theory}, year = {1992}, volume = {vol. 38}, number = {no. 1}, pages = {82--94}, url = {http://publik.tuwien.ac.at/files/pub-et_11014.pdf} }