In the article ['André Weil As I Knew Him'](http://www.ams.org/notices/199904/shimura.pdf) in the April 1999 issue of Notices of the AMS, Shimura recounts how in 1996 André Weil (then 90 years old) didn't remember a mistake of Minkowski. Specifically, quoting from mid-paragraph:


*"... In fact, to check that point, I asked him whether Minkowski was reliable. He said, 'I think so.' At that point I realized that his recollection was faulty, since Minkowski gave an incorrect formula, as Siegel pointed out, and that was known to most experts. ..."*


My question is:


**Where specifically in Siegel and Minkowski's published works can I find the aforementioned formula (of Minkowski) and observation (of Siegel)?**



What is Shimura referring to by "an incorrect formula given by Minkowski... known to most experts."
I believe he is referring to the result in Minkowski's dissertation that gives a formula for the mass (in the number/lattice theory sense) over a genus, that is, the sum of reciprocals of the group orders of all inequivalent quadratic forms in a genus. ([wikipedia](http://en.wikipedia.org/wiki/Smith%E2%80%93Minkowski%E2%80%93Siegel_mass_formula))


Siegel found and corrected the error in Minkowski's formula and also made many more generalizations in [this Annals paper](http://www.jstor.org/pss/1968644). Namely, there is an incorrect power of 2 in the formula. 


