Sidney van den Bergh's 1999 Review (The Early History of Dark Matter
) gives the landmark Zwicky paper as "Zwicky, F. 1933, Helvetica Phys. Acta, 6, 110", four years before the 1937 ApJ paper most folk remember (On the Masses of Nebulae and of Clusters of Nebulae, Astrophysical Journal 86, 217 - PDF
Nevermind, in the 1937 paper Zwicky not only introduces an application of the virial theorem as a means of estimating the mass in a (rich) cluster, but also gravitational lensing (he also discusses rotation curves in spirals!).
So, what is the 'virial theorem' method?
Observationally, one obtains the redshifts of as many galaxies - in the cluster of one's desire - as possible. The dispersion of these redshifts (crudely, the value of the standard deviation of the distribution of redshifts) is related to the (total) mass of the cluster, via the virial theorem
The kicker is, as Zwicky found for the Coma cluster, that there's (apparently) far more mass in the cluster than you'd expect, simply by 'counting (optical) photons' - i.e. from the kinds of stars that we know and love, from our observations of our own Milky Way galaxy.
Since 1937 a great many (rich) clusters have been observed (= redshifts of component galaxies obtained), and the estimates of ordinary ('baryonic') mass in the clusters constrained in many, often quite ingenious, ways. Perhaps the biggest revision came with the advent of x-ray astronomy: the galaxies in rich clusters swim in a pool of hot, tenuous plasma (mostly H) whose mass exceeds that of the galaxies (including their CDM!) by a factor of several.
Nevertheless, the conclusion remains the same: rich clusters have masses (estimated by 'the Zwicky (virial theorem) method') that are ~5 times higher than estimates of their total baryonic matter content.
To telegraph the next four categories of (very good) astronomical observation: several sets of quite independent observations corroborate the estimates of cluster mass obtained by 'the Zwicky (virial theorem) method'.
Note that Alfvén wasn't even 30 when Zwicky published his Coma cluster paper, and that dozens (possibly hundreds) of 'Zwicky (virial theorem) method' papers, on hundreds of clusters, were published during his working lifetime. Even more have been published in Perrat's working lifetime.
So: Which "EU theory" papers, published in relevant peer-reviewed journals, demonstrate quantitative consistency between 'theory' and 'Zwicky (virial theorem) method' astronomical observations of rich clusters of galaxies?