Where is the Erdős–Rado theorem stated in Erdős and Rado's Bull AMS paper? This may be inappropriate for MO, but here goes: if I have understood the statement of the Erdős–Rado theorem correctly, then it contains as a special case the following result:

if $\mu$ is an infinite cardinal then $(2^\mu)^+ \to (\mu^+)_\mu^2$

that is, every $\mu$-colouring of the $2$-elements subsets of a set $X$ of cardinality $> 2^\mu$ has a monochromatic subset of cardinality $>\mu$.
Looking online, the usual citation given for the ER-theorem is 
P. Erdős, R. Rado, A partition calculus in set theory. 
Bull. Amer. Math. Soc. 62 (1956), 427–489
I am trying to track down where in this paper one can find the statement of the E-R theorem, or at least the special case described above. Unfortunately, partition calculus lies well outside my usual routes for mathematical excursions, and some of the notation E&R use seems slightly at odds with the notation I see in all the various online notes describing or proving the E-R theorem. I am hoping that the set theorists among the MO readership may be more familiar with the notation of the paper and hence be able to quickly locate the statement.
 A: This is Theorem 39 in the paper (see Theorem 4.(i) for a user-friendly preview). But the fact that $(2^\kappa)^+\to(\kappa^+)^2_\kappa$ is older (1946) and due to Erdős, see here:

Paul Erdős. Some set-theoretical properties of graphs, Univ. Nac. Tucumán. Revista A. 3 (1942), 363-367 MR0009444 (5,151d).

(Anyway, it is probably easier to read a more modern presentation, such as in Paul Erdős, Andras Hajnal, Attila Máté, and Richard Rado. Combinatorial set theory: partition relations for cardinals, volume 106 of Studies in Logic and the Foundations of Mathematics. North-Holland Publishing Co., Amsterdam, 1984.)
There are still more modern presentations, using the language of elementary substructures, but if you are not familiar with it, this may not be too accessible.
A: It is also stated as Theorem 4.(i), I think, and again on pages 470 and 472 where the reference is given to earlier results.
For a recent easy-to-read presentation of the proof, see Theorem 5.1.4 in David Marker's Introduction to Model Theory.
