APA

lewis d., . (1984). PENCIL DRAWING TECHNIQUES. new york: watson-guptill publications.

Chicago

lewis david, . 1984. PENCIL DRAWING TECHNIQUES. new york: watson-guptill publications.

Harvard

lewis d., . (1984). PENCIL DRAWING TECHNIQUES. new york: watson-guptill publications.

MLA

lewis david, . PENCIL DRAWING TECHNIQUES. new york: watson-guptill publications. 1984.