We request but do not require that use of this software be cited in
publications as

Steve Rozen and Helen J. Skaletsky (2000)
Primer3 on the WWW for general users and for biologist programmers.
In: Krawetz S, Misener S (eds)
Bioinformatics Methods and Protocols: Methods in Molecular Biology.
Humana Press, Totowa, NJ, pp 365-386

Source code available at http://fokker.wi.mit.edu/primer3/.
The paper above is available at
http://jura.wi.mit.edu/rozen/papers/rozen-and-skaletsky-2000-primer3.pdf