“…More results on Colouring for (H 1 , H 2 )-free graphs can be found in a number of other papers [4,5,11,20,24,28,33,34,36], all of which are summarized in Theorem 3 given below, together with the above results and a weaker formulation of our new result (Statement (ii)-8). In this theorem, the graph C denotes the bull, which is the graph with vertices a, b, c, d, e and edges ab, ac, ad, bc, be and the graph C * 3 denotes the hammer, which is the graph with vertices a, b, c, d, e and edges ab, ac, ad, bc, de.…”