Heeffer, Albrecht. 2009. “On The Nature And Origin Of Algebraic Symbolism”. In New Perspectives on Mathematical Practices. Essays in Philosophy and History of Mathematics., New Perspectives on Mathematical Practices. Essays in Philosophy and History of Mathematics., Bart Van Kerkhove. World Scientific Publishing. http://www.worldscibooks.com/etextbook/6810/6810\_chap01.pdf.

Heeffer, Albrecht. 2008. “Negative Numbers As An Epistemic Difficult Concept. Some Lessons From History.”. In History and Pedagogy of Mathematics. Satellite Meeting of International Congress on Mathematical Education 11, 14 - 18 July 2008., History and Pedagogy of Mathematics. Satellite Meeting of International Congress on Mathematical Education 11, 14 - 18 July 2008., C. Tzanakis. Centro Cultural del México Contemporanéo.

Heeffer, Albrecht, and Harold Heeffer. 2007. “Near-Optimal Strategies For The Game Of Logik”.