Color mixing guide for artists, painters, decorators, printing pressmen, show card writers, sign painters, color mixers : gives color mixtures by parts (1923)
King, John L · New York : Ogilvie Pub. Co. · leaf 5
The above plates illustrate the primary and secondary colors broken up with light.
Paint mixing · Pigments · Colors
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.