H.-H. Van den Vlekkert, B. Kloeck, D. Kloeck, D. Prongue, J. Berthoud, B. Hu, N.F. De Rooij, E. Gilli, P.H. De Crousaz,
A pH-ISFET and an Integrated pH-Pressure Sensor with Back-Side Contacts Sensors and Actuators. ,vol. 14, pp. 165- 176 ,(1988) ,
10.1016/0250-6874(88)80063-5