By Herman Chernoff, credited as H. Chernoff in the institutional catalogue.
Repository identifier: purl.stanford.edu/sw496fn0032
The Stanford Statistics record gives report number SOL ONR 6 and report date November 1951. The catalogue metadata was inspected; the report's full text was not accessible during this pass. The record is cited for historical authorship and date, not as an inspected proof passage.
Stanford's archive records a technical report by Herman Chernoff, dated November 1951, on asymptotic efficiency of hypothesis tests based on sums of observations.[ref] This is historical source metadata, rather than a claim to have inspected the report's full proof. The modern theorem cited above connects that efficiency question to the log-likelihood ratio accumulated across repeated observations.