Unknown Author
Daniel Y. Gezari
Marion Schmitz
Giovanni G. Fazio
S. Alan Stern
Michael Rowan-Robinson
Martin Cohen
George H. Rieke
I. S. Glass
J. Ring
National Research Council
F. Sánchez
J. K. Davies
International School of Astrophysics Erice, Italy 1977.
C. G. Wynn-Williams
F. Casoli
Michael Werner
B. Jones