1. M. A. El-Sayed, this series, Vol. 88, p. 617.
2. R. Callender, this series, Vol. 88, p. 625.
3. R. Mathies, this series, Vol. 88, p. 633.
4. P. V. Argade; K. J. Rothschild, this series, Vol. 88, p. 643.
5. M. Braiman and R. Mathies, this series, Vol. 88, p. 648.