Alfeld, Peter (16 August 1996). "Why is the square root of 2 irrational?". Understanding Mathematics, a study guide. Department of Mathematics, University of Utah. பார்க்கப்பட்ட நாள் 6 February 2013.
utexas.edu
cs.utexas.edu
Stone, Peter. "Logic, Sets, and Functions: Honors"(PDF). Course materials. pp 14–23: Department of Computer Sciences, The University of Texas at Austin. பார்க்கப்பட்ட நாள் 6 February 2013.{{cite web}}: CS1 maint: location (link)