[Laidlaw et al., 1998]
David H. Laidlaw, davidkremers, Eric T. Ahrens, and Matthew J. Avalos. Visually Representing Multi-valued Scientific Data Using Concepts from Oil Painting. In SIGGRAPH '98 Visual Proceedings (sketch), page 249, August 1998. (pdf) (bibtex: Laidlaw-1998-VRM).