Q. How do I locate the publisher and publishing date of a book? Also, what is meant by medium?

The publisher is usually found on the bottom half of the book's title page at the front of the book (not the cover). The date is usually on the back of the title page. It is okay to use the most recent copyright date as the publishing date. The medium just refers to the type of item you are using, in this case a "book." Others could be a periodical (paper) or an electronic article or a DVD, etc.