Citation, Documentation of Sources
Q. How should I cite in the text multiple publications by the same author? Can I simply write (Sutinen 1969, 1976, 1981)? Or should I write (Sutinen 1969, Sutinen 1976, Sutinen 1981)?
A. Though there’s a risk that the additional years might be misread as page numbers (at least initially), your first approach is preferred for its brevity. But if page numbers are also cited, use semicolons instead of commas: (Sutinen 1969; 1976, 257; 1981). See CMOS 15.30 for more details and examples.