Second neighbourhoods of strongly regular graphs. - Anthony D. Gardiner; Chris D. Godsil; A. D. Hensel; Gordon F. Royle (Discret. Math., 1992)

On 4-Valent Symmetric Graphs. - Anthony D. Gardiner; Cheryl E. Praeger (Eur. J. Comb., 1994)

A Characterization of Certain Families of 4-Valent Symmetric Graphs. - Anthony D. Gardiner; Cheryl E. Praeger (Eur. J. Comb., 1994)