in 1994 robinson (now aged 83!) published two figures in the hyperbolic plane which presents some properties of tilings of the hyperbolic plane by equilateral triangles having angles of size 2/n, where n = 7 or n = 9.

Make this proper case.
In 1994 Robinson (now aged 83!) published Two figures in the hyperbolic plane which presents some properties of tilings of the hyperbolic plane by equilateral triangles having angles of size 2/n, where n = 7 or n = 9.