by Boothby, W.M., Marino, R.
Published in Proceedings of the 28th IEEE Conference on Decision and Control (1989)

by Dayawansa, W., Boothby, W.M., Elliott, D.L.
Published in Systems & control letters (01.01.1985)

by Boothby, W.M, Wang, H.-Ch
Published in Commentarii mathematici Helvetici (1964)