Complex sentence: Any toroidal graph has chromatic number at most 7 (Heawood 1890) and any triangle-free toroidal graph has chromatic number at most 4 (Kronk and White 1972).
Split into simpler sentences: Any toroidal graph has chromatic number at most 7 (Heawood 1890). Any triangle-free toroidal graph has chromatic number at most 4 (Kronk and White 1972).