Peter A. Erkelens
- A process time information system (PTIS) for productivity improvement. Vorgetragen bei: IABSE Workshop: Organization of the Design Process = Organisation du processus du projet = Organisation des Planungsprozesses, Zurich, Switzerland, 1986. (1986):
- Productivity and productivity factors in the builidng industry. In: IABSE Journal, v. 8 ( 1984). (1984):