<?php
	$current_cat = get_query_var('cat');
	// for tags use 'tag'
	// $current_tag = get_query_var('tag');

	$args = array(
	  'cat' => $current_cat,
	  // 'tag' => $current_tag,
	  'post_type' => 'post',
	  'posts_per_page' => 1
	);

	$the_first_query = new WP_Query( $args );
	// The Loop
	while ( $the_first_query->have_posts() ) : $the_first_query->the_post();
		the_title();
	endwhile;

	// Reset Post Data
	wp_reset_postdata();

	$args = array(
	  'cat' => $current_cat,
	  // 'tag' => $current_tag,
	  'post_type' => 'book',
	  'posts_per_page' => 1
	);

	$the_second_query = new WP_Query( $args );
	// The Loop
	while ( $the_second_query->have_posts() ) : $the_second_query->the_post();
		the_title();
	endwhile;

	// Reset Post Data
	wp_reset_postdata();
?>