A project in algorithms based on a primary historical source about catalan numbers. - David Pengelley; Inna Pivkina; Desh Ranjan; Karen Villaverde (SIGCSE, 2006)

Did Euclid Need the Euclidean Algorithm to Prove Unique Factorization? - David Pengelley; Fred Richman (Am. Math. Mon., 2006)

Quick, Does 23/67 Equal 33/97? A Mathematician's Secret from Euclid to Today. - David Pengelley (Am. Math. Mon., 2013)

What Does "Less Than or Equal" Really Mean? - Guram Bezhanishvili; David Pengelley (Am. Math. Mon., 2015)