Conference paper
Constraint-based query optimization for spatial databases
Richard Helm, Kim Marriott, et al.
SIGMOD/PODS/ 1991
Paper
Ensuring Semantic integrity of reusable objects (panel)
Related
Richard Helm, Yoëlle S. Maarek
ACM SIGPLAN Notices
Conference paper
Visualizing the behavior of object-oriented systems
Wim De Pauw, Richard Helm, et al.
OOPSLA 1993
Richard Helm, Ian M. Holland, et al.
ECOOP 1990