IEEE TRANSACTIONS ON AUTOMATIC CONTROL, vol. 44, no. 11, page. 2115 - 2120, 1999-11
IEEE TRANSACTIONS ON AUTOMATIC CONTROL, vol. 44, no. 9, page. 1787 - 1791, 1999-09
IEEE TRANSACTIONS ON AUTOMATIC CONTROL, vol. 44, no. 4, page. 876 - 877, 1999-04
INTERNATIONAL JOURNAL OF CONTROL, vol. 72, no. 5, page. 385 - 391, 1999-03-20
SYSTEMS & CONTROL LETTERS, vol. 36, no. 1, page. 15 - 20, 1999-01-12