Dates
If no date can be established you can use n.d.
If the date can be established but only approximately you should use c.
Page numbers
Electronic books read via an e-reader such as the Kindle do not have traditional page numbers. In this case, if you need to use a quotation from this source, use the chapter numbers for indicating the location of the quoted section:
If you wish to cite a web resource that does not include page numbers, you can include any of the following in the text to cite the quotation:
• A paragraph number, if provided; alternatively, you could count paragraphs down from the beginning of the document:
• An overarching heading plus a paragraph number within that section:
• A short title in quotation marks, in cases in which the heading is too unwieldy to cite in full:
A PDF is a format rather than a type of resource. You should reference this according to the source type, but if this is not possible, you can reference as a website.