public function checkColumns($book, $row_number, CheckLinks &$check_links, Authors $authors)
{
$this->onRow($row_number + 2);
$this->checkColumnCount($book);
$book_title = $book['title'];
$this->checkCharacters($book_title, 'A-Title');
$book_author = $book['author'];
$this->checkCharacters($book_author, 'B-Author');
$story_link = $book['story_link_on_wikipedia'];
$this->checkWikipediaLink($story_link, 'C-Story Link on Wikipedia');
$check_links->addUrl($story_link);
$author_link = $book['author_wikipedia_entry'];
$this->checkWikipediaLink($author_link, 'D-Author Wikipedia Entry');
$check_links->addUrl($author_link);
$authors->addAuthorCollapsed($book_author, $author_link);
$this->checkPdfColumns($book, $check_links);
}