1. von Karman, Th., and Biot, M. A., Mathematical Methods in Engineering, 1st Ed., pp.370-378; McGraw-Hill Book Company, Inc., 1940.
2. Coupled Oscillations of Aircraft Engine-Propeller Systems
3. Kron, Gabriel, Tensor Analysis of Networks, pp.7-13; John Wiley & Sons, Inc., 1939.
4. Elementary Matrices
5. Kron, Gabriel, op. cit., pp.257-258.'