- Bureau of Labor Statistics, U.S. Department of Labor (2006). "Engineers". Occupational Outlook Handbook, 2006–07 Edition. 喺2006-09-21搵到.
- National Society of Professional Engineers (2006). "Frequently Asked Questions About Engineering". （原先內容喺22 May 2006歸檔）. 喺2006-09-21搵到. "Science is knowledge based on our observed facts and tested truths arranged in an orderly system that can be validated and communicated to other people. Engineering is the creative application of scientific principles used to plan, build, direct, guide, manage, or work on systems to maintain and improve our daily lives."