@article{TUW-103182, author = {Hlawatsch, Franz and B{\"o}lcskei, Helmut}, title = {Covariant time-frequency distributions based on conjugate operators}, journal = {IEEE Signal Processing Letters}, year = {1996}, volume = {vol. 3}, number = {no. 2}, pages = {44--46}, url = {http://publik.tuwien.ac.at/files/pub-et_3416.pdf} }