Parse authors of the book.

    Args:
        details (obj): HTMLElement containing slice of the page with details.

    Returns:
        list: List of :class:`structures.Author` objects. Blank if no author \
              found.

def _parse_authors(details):
    """
    Parse authors of the book.

    Args:
        details (obj): HTMLElement containing slice of the page with details.

    Returns:
        list: List of :class:`structures.Author` objects. Blank if no author \
              found.
    """
    authors = details.find(
        "tr",
        {"id": "ctl00_ContentPlaceHolder1_tblRowAutor"}
    )

    if not authors:
        return []  # book with unspecified authors

    # parse authors from HTML and convert them to Author objects
    author_list = []
    for author in authors[0].find("a"):
        author_obj = Author(author.getContent())

        if "href" in author.params:
            author_obj.URL = author.params["href"]

        author_list.append(author_obj)

    return author_list