Mihalov، J. D.؛ Collard، H. R.؛ Intriligator، D. S.؛ Barnes، A. (1987). "Observation by Pioneer 7 of He+ in the distant coma of Halley's comet". Icarus. ج. 71: 192–197. Bibcode:1987Icar...71..192M. DOI:10.1016/0019-1035(87)90172-2.
Mihalov، J. D.؛ Collard، H. R.؛ Intriligator، D. S.؛ Barnes، A. (1987). "Observation by Pioneer 7 of He+ in the distant coma of Halley's comet". Icarus. ج. 71: 192–197. Bibcode:1987Icar...71..192M. DOI:10.1016/0019-1035(87)90172-2.