1. What to expect from direct-digital control;Williams;Chem. Engng,1964
2. Guidelines and General Information on User Requirements Concerning Direct Digital Control,1963
3. Questions and Answers on Direct Digital Computer Control,1963
4. Computer Equipment for Direct Digital Control,1965
5. Progress in chemical process control in America: Computers, instrumentation, and applications;Williams;Trans. Instn Chem,1963