All style guides have provision for citing electronic documents that do not have page numbers. It is not necessary to find a print edition to cite. The Chicago Manuarl of Style Online says the following:
13.2
Sources consulted in electronic formats will not always include page numbers. When that is the case, it may be appropriate in a note to include a chapter or paragraph number (if available), a section heading, or a descriptive phrase that follows the organizational divisions of the work. In citations especially of shorter electronic works presented as a single, searchable document, such locators are often unnecessary. See also
14.59: Page numbers in ebooks
Many ebook formats feature reflowable text without fixed page numbers. Depending on the application and on the book itself, information about location within the book may vary according to user-defined text size, making any reference to such information unhelpful to others wishing to consult the same place in the text. Even when a book provides fixed location numbers, these may be helpful only to those who consult the same ebook format. It is therefore often best to cite a chapter number or a section heading or other such milepost in lieu of a number. (But if paragraphs are numbered, as in this manual, those can be cited.)
Some ebooks feature page number data corresponding to a printed edition of the same work. Where this is the case, page numbers may be cited in the usual way. Bear in mind, however, that unless page breaks corresponding to the print edition are displayed in some way, such references may be off by a page. (If possible, check page numbers against the printed version.)
