1. I.S. Dring, R. Devonshire, J. Meads, H.F. Boysan and D.A. Greenhalgh, to be published.
2. D.A. Greenhalgh, R. Devonshire, I.S. Dring and H.F. Boyson, to be published.
3. H.F. Boysan, R. Devonshire, I.S. Dring, D.A. Greenhalgh and D.O. Wharmby, patent applied for.