Burkman, J. ., Grindle, G. ., Wang, H. ., Kelleher, A. ., & Cooper, R. . (1969). Further Development of a Robotic-Assisted Transfer Device. Topics in Spinal Cord Injury Rehabilitation, 23(2), 140-146. https://doi.org/10.1310/sci2302-140 (Original work published 1969)