Warning: Trying to access array offset on value of type null in book_prev() (line 787 of /mnt/web207/a3/11/547011/htdocs/portal/drupal/modules/book/book.module).
Warning: Trying to access array offset on value of type null in book_prev() (line 791 of /mnt/web207/a3/11/547011/htdocs/portal/drupal/modules/book/book.module).
Notice: Only variables should be passed by reference in eval() (line 4 of /mnt/web207/a3/11/547011/htdocs/portal/drupal/modules/php/php.module(80) : eval()'d code).