@booklet {NASAsemiannual:1991a, title = {{NASA Semi-Annual Report on Control of Free-Flying Space Robot Manipulator Systems}}, number = {10}, year = {1991}, month = {February}, publisher = {Stanford University Aerospace Robotics Lab}, address = {Stanford, CA 94305}, author = {Robert H. Cannon Jr. and Marc Ullman and William Dickson and Lawrence Alder and Edward Wilson and Kurt R. Zimmerman} }