Tomás Isakowitz Shimon Schocken Henry C. Lucas Jr. Toward a Logical/Physical Theory of Spreadsheet Modeling. 1-37 1995 13 ACM Trans. Inf. Syst. 1 http://doi.acm.org/10.1145/195705.195708 db/journals/tois/tois13.html#IsakowitzSL95