See abstr. A11994 of 1974. Further details are given of a graphical approach to the Gel'fand-Yaglom equations and their quantization, in the case when repeated representations are not allowed. Graphs associated with the s blocks of L₀ are used in their construction, in writing down their characteristic polynomials and the traces required in the quantization conditions. As well as being useful as practical procedures, the methods described are more suggestive theoretically than the conventional algebraic treatment. As examples a range of quantizable spin-2 theories are obtained. It is shown that it is possible to obtain various mass spectra and yet still have a quantizable theory. It is proved that the representation (-1,j+1)(+)(0,j+1)(+)(1,j+1) must occur in a good quantizable theory with maximum spin j not=0.