Bureau of Labor Statistics, U.S. Department of Labor. Engineers. Occupational Outlook Handbook, 2006-07 Edition. 2006 [2006-09-21]. （原始内容存档于2006-02-19）.
National Society of Professional Engineers. Frequently Asked Questions About Engineering. 2006 [2006-09-21]. （原始内容存档于2006-05-22）. Science is knowledge based on 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.
National Society of Professional Engineers. Frequently Asked Questions About Engineering. 2006 [2006-09-21]. （原始内容存档于2006-05-22）. Science is knowledge based on 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.
Bureau of Labor Statistics, U.S. Department of Labor. Engineers. Occupational Outlook Handbook, 2006-07 Edition. 2006 [2006-09-21]. （原始内容存档于2006-02-19）.
