In the paper Zur Hilbertschen Beweistheorie, John Von Neumann has proposed a consistency proof for a fragment of first-order arithmetic (the fragment without induction and with the successor axioms only) by a variant of Hilbert's substitution method.
The paper is in German, and I so could not read it.
Question 1. Can anyone explain the main ideas of Von Neumann's work in this paper?
Question 2. Are there any references in English, explaining Von Neumann's work in details?