The contributions of the following persons are acknowledged: G. Allard, J. Bentley, M. Bigger, W. Ciesla, F.A. Ferreira, S. Fortuna, I. Gibson, M. Guardia, B. Hall, C. Hodges, M. Holderness, A. Maisharou, E. Magarinos, A. Perlis, M. Perri, M. Speight, J. Sutherland, D. Vasques, J. Waller, M. Wingfield and S. Woodward.
C. Hodges and J. Sutherland are especially thanked for the use of their photographs.
