[by] R. Jenkins [and] J. L. de Vries. by A. R. Penfold and J. L. Willis. by M. H. Atkins and J. F. Lowe. by R. Davies and E. R. Austin. by K. J. Binns and P. J. Lawrenson. by R. Belcher and A. L. Godbert. by R. A. Robinson and R. H. Stokes. by R. G. Selfridge and J. E. Maxfield. by R. Courant and D. Hilbert. by B. W. Preece and J. D. Davies.