Joint torque sensory feedback in the control of a PUMA manipulator. - Lawrence E. Pfeffer; Oussama Khatib; John Hake (IEEE Trans. Robotics Autom., 1989)

Experiments with a Dual-Armed, Cooperative, Flexible-Drivetrain Robot System. - Lawrence E. Pfeffer; Robert H. Cannon Jr. (ICRA (3), 1993)