American Mathematical Monthly

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. To fix these ideas we proceed to the construction of the non-primitive groups of degree six which contain three systems of non-primitivity. We shall then have found all the non-primitive groups up to degree eight as no such groups can'exist for degree seven, or any other prime degree.