Michel Jacobs (1877-1958), Director, Metropolitan Art School of New York & the Metropolitan Color Guild of New York - 'The art of colour' (1923). Garden City, NJ: Doubleday, Page & Company. https://archive.org/details/artofcolour0000jaco/ 'The study of color, with lessons and exercises, arranged for instruction of teachers, artists, students and parents' (1925). New York: D. Van Nostrand - features 80+ color exploration exercise templates. https://archive.org/details/studyofcolorwith00jaco/