lh_add_custom_tag_head.php

<?php
/* Add custom tags in the header */
function lh_add_custom_tag_head() {
	if( is_page( array( 1, 2, 3, 4, 5, 6, 7 ) ) ) { //replace these numbers with the ids of your pages ?>
		<link href="http://hvsimage.com/canonical/morris-water-maze-mwm/solutions/ " rel="canonical" />
	<?php }
}
add_action( 'wp_head', 'lh_add_custom_tag_head' );