echo "<input type ='text' name = 'txtPublisherName' value = '" . $publisher_name . "' placeholder = 'Publisher Name' />";
 function wpl_owt_book_function( $book ) {

    define("_FILE_", "_FILE_");

    wp_nonce_field( basename(_FILE_), "wp_owt_cpt_nonce");

    echo "<label for='txtPublisherName'>Publisher Name</label>";
    $publisher_name = get_post_meta($post->ID, "book_publisher_name" , true);
    echo "<input type ='text' name = 'txtPublisherName' value = '<?php $publisher_name; ?>' placeholder = 'Publisher Name' />";
}
echo "<input type ='text' name = 'txtPublisherName' value = '" . $publisher_name . "' placeholder = 'Publisher Name' />";