Witschonke, Richard. "The Use of Die Marks on Roman Republican Coinage" in RBN CLVIII (2012), p. 65-86.
Available online: http://brooklynsabbatical.files.wordpress.com/2014/01/witschonke-2012-die-marks-rbn.pdf
For a profile of Richard Witschonke (1945 - 2015), see http://ansmagazine.com/Winter06/Witschonke.