Appendix B: Documentation of Sources

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This appendix discusses when and how to reference the work of others. Referencing is important in engineering and science. Failure to reference the work of others has brought discredit to numerous authors. At this site, the method for referencing sources is an author/year referencing system, which is a common one in engineering and science. This system is by no means the only system in engineering and science. To view other systems, please refer to the following referencing link.

What Sources to Reference

Use references to credit the ideas, measurements, computations, or writings of others. In engineering and science, these types of references occur often.

In the meeting, Richard Feynman [1986] proposed that the cold temperatures affected the resiliency of the booster rocket's O-rings.

In 1862, Foucalt measured the speed of light to be 2.98 10E8 meters/second [Halliday and Resnick, 1974].

The Energy and Environmental Policy Center at Harvard University calculated that the average person was three times more likely to die from lightning than from asbestos in school buildings [Cary, 1995].

The Department of Energy [1988] released a preliminary report that assessed the health hazards at sixteen nuclear weapon plants.

Use references to credit the wording of others. In engineering and science, quotations are not used nearly as often as paraphrases are. When are quotations used? You quote someone else's words in the following circumstances: (1) when the wording is unusual and you can find no more precise way to state the idea; (2) when the person who says the words is a recognized authority and you want that person's name on the page supporting your arguments; or (3) when the wording has to be precise, such as in a law or statute. Given below is an example of the first case:

Glenn T. Seaborg, former chairman of the Atomic Energy Commission, described NERVA's reactor as "a flyable, compact reactor, not much bigger than an office desk, that will produce the power of Hoover Dam, from a cold start, in a manner of minutes" [Borowski and others, 1989].

When the quotation is long (three or more lines), then it is set off with spacing and indents. Note that the set-off quotation is single-spaced and has no quotation marks.

Responding to the charges of polluting the groundwater, the plant manager of Pantex, Dr. Clyde Alley [1989], said the following:
There is no evidence that Pantex Plant operations have contaminated the Ogalla Aquifer or any public land surrounding the plant. In fact, test results indicate that we have not.

Use references to back up assertions in your writing. To back up assertions in your writing, you often use references for controversial ideas, even though the ideas might appear to be common knowledge to you.

Compared with the large objects of operational debris, the microparticulate matter might appear to be a negligible threat. However, these particles obtain high orbital speeds that increase their threat to space activity [DeMeis, 1987].

Use references to credit the illustrative concepts, art, or photography of others. The following three examples present cases for a figure (Figure B-1), a table (Table B-1) in which all the data comes from one source, and a table (Table B-2) in which the data comes from various sources.

Figure B-1. Wind tunnel and diagnostic equipment to measure flow fields, thermal fields, and surface heat transfer [Thole, 2000].

Table B-1. Physical characteristics of planets [Handbook, 1969].
Planet Diameter
(earth ratio)
(earth days)
Mercury 5,100 0.40 88 700
Venus 12,600 0.90 225 700
Earth 12,800 1.00 365 350
Mars 6,900 0.40 687 320
Jupiter 143,600 2.70 4,333 150
Saturn 120,600 1.20 10,759 138
Uranus 53,400 1.00 30,686 90

Table B-2. Comparison of criteria for two propulsion systems.
Propulsion System Specific Impulse
Flexibility Cost
Nuclear thermal rockets [Winter, 1990] 850 50,000 High Medium
Electric ion rockets [Phillips, 1987] 5000 10 High Medium

You do not have to reference common knowledge. As long as the information is not controversial and is contained in multiple sources, you do not have to reference that information. Categories of such information are commonly used numbers, dates of historic events, and generally accepted assertions and facts. Examples from these categories are given below:

The speed of light is 3 X 10E8 meters per second. (not someone's specific measurement)

Roentgen discovered x-rays in 1895.

The properties of a material originate from the internal structures of that material.

The nucleus of an atom is composed of protons and neutrons.

How to Reference Sources

Once you have given a reference listing in the text of the document, you are obligated to give a full reference citation somewhere in the document (usually at the end). Just as there are different ways to give reference listings in the text (author/year, numbers, and so forth), there are different formats for reference citations. Given below is a common system used in engineering and science for the reference listings of this appendix. For an explanation of the form of this system, see Appendix A.


Alley, C. D., Plant Manager of Mason-Hanger Pantex Plant (Amarillo, TX: 3 March 1989), letter to Amarillo Globe News.

Asker, J. R., "Nuclear Rockets Gain Support for Propelling Mars Mission," Aviation Week & Space Technology, vol. 134 (18 March 1991), pp. 78-79.

Borowski, S.K., E.A. Gabris, and J. Martinelli, "Nuclear Thermal Rockets: Next Step to Space," Aerospace America, vol. 127, no.2 (February 1987), pp. 16-18.

Cary, Peter, "The Asbestos Panic Attack," U.S. News & World Report (20 February 1985), p. 62.

DeMeis, R., "Cleaning up Our Space Act," Aerospace America, vol. 127, no. 2 (February 1987), pp. 10-11.

Department of Energy, Preliminary Report on the Assessment of Health Risks From the United States Nuclear Weapon Facilities, DOE Report #88-805P (Washington, DC: Department of Energy, 1988).

Feynman, Richard P., "An Outsider's Inside View of the Challenger Inquiry," Physics Today (February 1988), pp. 26-37.

Halliday, David, and Robert Resnick, Fundamentals of Physics (New York,: Wiley, 1974), p. 655.

Handbook of Chemistry and Physics, 50th ed. (New York: Chemical Rubber Publishing Co., 1969).

Kare, Jordan T., Laser Propulsion and Possible Mission to Mars, AAS (Livermore, CA: Lawrence Livermore National Laboratory, 1987).

"Solar Photon Thruster," Journal of Spacecraft and Rockets, vol. 28, no. 4 (July-August 1990), pp. 411-416.

Thole, Karen, "Facilities of the Experimental and Computational Convection Laboratory," (Blacksburg, VA: Virginia Tech, 2000).

Winter, Frank, Rockets Into Space (Cambridge, MA: Harvard University Press, 1990).

Last updated 02/2006
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