Klausenburger, Jurgen (1987). "Review of Umlaut in Romance. An Essay in Linguistic Archeology. Giessener Beiträge zur Sprachwissenschaft, 12, CLIFFORD S. LEONARD JR". Romance Philology. 40 (3): 366–369. ISSN0035-8002. JSTOR44943385.
Klausenburger, Jurgen (1987). "Review of Umlaut in Romance. An Essay in Linguistic Archeology. Giessener Beiträge zur Sprachwissenschaft, 12, CLIFFORD S. LEONARD JR". Romance Philology. 40 (3): 366–369. ISSN0035-8002. JSTOR44943385.