G. Burdea and N. Langrana, “Virtual Force Feedback A Lessons, Challenges, Future Applications,” J. Robot.: Mechatron.: Vol.5, No.2.1993 ppS.178-182.:  .. 1993. --
G. Burdea and N. Langrana, “Virtual Force Feedback Lessons, Challenges, Future Applications,” J. Robot. Mechatron., Vol.5, No.2, pp. 178-182, 1993.