Citation, Documentation of Sources

Q. Hello—For my dissertation, I am citing many Italian books from the seventeenth and eighteenth centuries. Many contain prefaces, but they are almost never called by that name. Most of the time, they are dedications to so and so. What is worse, they often do not have page numbers. So if I take a specific quote from somewhere in the dedication, should I write the name of the dedication and then the page number (based on the pages I counted)? This is from a preface, so shouldn’t I then use roman numerals in the lower case, iii? So the entry might look like this:

Giovanni B. Donado, Raccolta curiosissima d’adaggi turcheschi (Poletti, 1688). (“Illustriss. Sig. Sig. e Patron Colendissimo”), iii.

I would greatly appreciate your help on this.

A. There is usually no need to include the title of a preface or dedication in a citation or to identify it as such, but when there are no page numbers, it is probably a good idea:

Giovanni B. Donado, “Illustriss. Sig. Sig. e Patron Colendissimo,” dedication in Raccolta curiosissima d’adaggi turcheschi (Poletti, 1688), [3].

Cite the page number in the same way you normally would, but put brackets around any page number that is not expressed. If the entire book is unpaged, it would confuse things to use roman numerals for the front matter, especially if you go on to cite another page in arabic numerals, since readers would have no way to know for sure on which page your imaginary numbers change from roman to arabic. If the main part of the book has expressed arabic numerals, however, then to avoid confusion with the expressed page 3, use roman numerals in brackets for the unpaginated front matter.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]