citation One of the initial exact values established by Greenwood & Gleason in 1955 (survey DS1, section 2.1(b), attributes R(3,4)=9, R(3,5)=14 and R(4,4)=18 to [GG]). Every 2-coloring of K_9 contains a red K_3 or a blue K_4, and a K_8 coloring witnesses the lower bound.