Illustration and Language in Technical Communication
http://baywood.metapress.com/link.asp?target=contribution&id=HY3LWN98QC5RP3B3
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  peer-reviewed

Donnell, Jeffrey
Journal of Technical Writing and Communication
2005

Abstract:

Many technical documents present information both graphically and verbally. While much is known about the verbal tools of technical professionals, technical graphics have been less fully examined. Here the drawings of a United States patent are examined revealing a system for organizing and presenting visual information that is analogous to commonly-used models for organizing and presenting verbal information.