The use ofV,WandXcoefficients in calculations of matrix elements is shown. General formulae for all two-electron spin-orbit coupling matrices in an octahedral strong-field coupling scheme are deduced. The parametrization of the electrostatic energy in ligand field theory is discussed and the number of parameters required is given in various cases. The configurationf2in an octahedral strong-field scheme is treated in some detail and reasons for the anomalously low paramagnetism of PuF6are exposed, largely in contradiction to earlier views [13, 14]. Finally it is shown that expressions involving recoupling matrix elements, which occur in a scheme for calculating matrix elements of one-electron operators given by Tanabe and Kamimura [3], are proportional toWandXcoefficients, thus considerably extending the scope of the latter work.