@Article{AbrEriKoi08TSP,
  author = 	 {T. Abrudan and J. Eriksson and V. Koivunen},
  title = 	 {Steepest Descent Algorithms for Optimization Under Unitary Matrix Constraint},
  journal = 	 {IEEE Transaction on Signal Processing}, 
  year = 	 {2008},
  volume = 	 {56},
  number = 	 {3},
  pages = 	 {1134--1147},
  month = 	 {Mar.},

}