1. Baecker R. Towards an effective characterization of graphical interaction IFIPS Workgroup 5.2 (CAD) meeting May 1979 Seillac (Paris) Baecker R. Towards an effective characterization of graphical interaction IFIPS Workgroup 5.2 (CAD) meeting May 1979 Seillac (Paris)
2. Definition and use of higher-level graphics input tools
3. Hopgood F. K. and Duce D. A. A production system approach to interactive graphic program design IFIPS workgroup 5.2 (CAD) meeting May 1979 Seillac (Paris) Hopgood F. K. and Duce D. A. A production system approach to interactive graphic program design IFIPS workgroup 5.2 (CAD) meeting May 1979 Seillac (Paris)
4. The semantics of graphical input