1. P. J. W. Hyde, Rubb. Plast. Age. 50 (1969) 654.
2. A. Hepworth, T. Buckley, and J. Sikorski, J. Sci. Instr. (J. Phys. E) 2 (ser. 2) (1969) 789.
3. J. W. S. Hearle, and P. M. Cross, Textile Inst. Ind. 7 (1969) 213.
4. P. Cross, J. W. S. Hearle, B. Lomas, and J. Sparrow, Proc. Third Annual Scanning Electron Microscope Symposium, Chicago (1970).
5. P. H. Newman and J. Sikorski, Electron Microscopy, Proc. 4th Europe. Reg, Conf. on Electron Microscopy, Rome. Vol. 1 (1968) p. 549.