The Phaidon Press, with the series of fine art books at prices within the range of many pocket-books, shares responsibility with the exhibitions at the two World's Fairs (and elsewhere), for the mushroom growth of popular interest in art books. Two new titles (above) are on the water; publication date uncertain. MASTERPIECES OF EUROPEAN PAINTINGS IN AMERICA (with 300 reproductions) has been recently published. And two more titles, for late Fall publication, are scheduled, THE PAINTINGS OF MICHELANGELO and THE SCULPTURES OF MICHELANGELO (120 plates each).