def get_quote_book(quote_div):
    """Get the reference (book) from a ``<div>`` quote element.

    Args:
        quote_div (bs4.element.Tag): ``<div>`` quote element from a quote page.

    Returns:
        bs4.element.Tag

    """
    quote_details = quote_div.find('div', attrs={'class': 'quoteText'})
    return quote_details.find('a', attrs={'class': 'authorOrTitle'})