Balkwill, Ray. Watercolour plus : enhance your watercolours with other media / edited by Ray Balkwill. - Newton Abbot : David & Charles, 2002. - 128 p. : col. ill. ; 28 cm. Includes index. Soft pastel -- Textures -- Gouache -- Pen and ink -- Oil pastel -- Collage. ISBN: 0715312537 (hbk.) 9780715312537 (hbk.) Subjects--Topical Terms: Watercolor painting--Technique. Dewey Class. No.: 751.422 / BAL