1. Chen, P., & Ruiz-Altisent, M. (1993). Effect of impacting mass on firmness sensing of fruits. ASAE paper no. 93-6542
2. Chen, P., & Ruiz-Altisent, M. (1996). A Low-mass impact sensor for high-speed firmness sensing of fruits. Paper presented at AgEng 96, Madrid, Paper no. 96F-003
3. Chen, P., & Tjan, Y. (1998). A real-time impact sensing system for on-line firmness sensing of fruits. Paper 98-F-006 presented at AgEng 98, Oslo
4. Chen, P., Sarig, Y., & Thompson, J. F. (2000). A hand-held impact sensor for firmness sensing of fruits. Postharvest 2000, Jerusalem, March 26–31
5. Garcı́a, C., & Ruiz-Altisent, M. (1988). Impact parameters related to bruising in selected fruits. ASAE paper no. 88-6027