W. Fisher

Part and Assembly Description Languages--II: definitional facilities in PADL-1.n and command facilities in the PADL-1.0/2.n processor

Aristides A. G. Requicha, Herbert B. Voelcker, N. M. Samuel, 1978 .

The PADL-1.0/n Processor: Overview & System Documentation

Aristides A. G. Requicha, Herbert B. Voelcker, Eugene Hartquist, 1977 .