Four color toners of yellow, magenta, cyan and black, and four two-component developers containing the four color toners respectively in combination with a resin-coated ferrite carrier suitable for multi-color electrophotographic copying are provided. Each of the four-color toners is strictly regulated...http://www.google.de/patents/US5149610?utm_source=gb-gplus-sharePatent US5149610 - Color toner and two-component developer containing same
