Seigensha
Seigensha is a stationery brand from Japan, made by Seigensha Art Publishing, Inc. 1 guide to Seigensha products.
Seigensha guides and roundups
A Dictionary of Color Combinations: Sanzo Wada, Vol. 1 & 2
Sanzo Wada's A Dictionary of Color Combinations explained: 348 color sets with CMYK values, how Vol. 2 differs, the 1930s original and where to buy in the US.