the reference is,
Klechkowski, V.M., Doklady Akademii Nauk, 86: 691-694, 1951.
If not I have a number of other references by this author which may be what you are looking for.
Interestingly the rule, by whichever name one might call it, has yet to be derived from first principles.
There have been attempts by the likes of Lee Allen (to my mind spurious), Obadasi, Hakala, and by Ostrovsky. None of them appear to be very convincing.
I have written about this in the first of the two volumes dedictated to Lowdin (Kluwer, 2003), and in another paper in Foundations of Chemistry, vol 6, No1, 93-116, 2004.
One of Ostrovsky's paper's on this subject with a full bibliography of the early formulation of the rule also appears in the same journal. vol 3, 145-182, 2001.
On Sep 28, 2005, at 9:07 AM, CCL wrote: