Giorgio Germano Andrea Maggiolo-Schettini Recursivity, Sequence Recursivity, Stack Recursivity and Semantics of Programs. 52-64 1976 conf/mfcs/1976 MFCS db/conf/mfcs/mfcs76.html#GermanoM76 http://dx.doi.org/10.1007/3-540-07854-1_161