Candiotti, J., Sundaram, S., Daveler, B., Gebrosky, B., Grindle, G., Wang, H., & Cooper, R. (1969). Kinematics and Stability Analysis of a Novel Power Wheelchair When Traversing Architectural Barriers. Topics in Spinal Cord Injury Rehabilitation, 23(2), 110-119. https://doi.org/10.1310/sci2302-110 (Original work published 1969)

Sundaram, S., Wang, H., Ding, D., & Cooper, R. (1969). Step-Climbing Power Wheelchairs: A Literature Review. Topics in Spinal Cord Injury Rehabilitation, 23(2), 98-109. https://doi.org/10.1310/sci2302-98 (Original work published 1969)