1. W. Laurie, Med. J. Aust., 1 (1971), 1224–6.
2. G. E. Burch and T.D. Giles, Am. J. Med., 50, (1971), 141–5.
3. L. Gould, Am. Heart J., 84, (1972), 13.
4. J. Hognestard and P. Teisberg, Acta. Path, miciobiol Scand., 81A, (1973), 315–22.
5. L. A. Schenk and J. Cohen, Pathologia Microbiol. (Basel), 35, (1970), 96–104.