I am looking for a reference to the paper where k-fold cross-validation was introduced (rather than just a good academic reference for the subject). Perhaps it is too far back in the mists of time to unambiguously identify the very first paper, so any early papers where the idea was used would be of interest.
The earliest I am aware of are
P. A. Lachenbruch and M. R. Mickey, “Estimation of error rates in discriminant analysis,” Technometrics, vol. 10, no. 1, pp. 1–12, Feb. 1968.
A. Luntz and V. Brailovsky, “On estimation of characters obtained in statistical procedure of recognition (in Russian),” Techicheskaya Kibernetica, vol. 3, 1969.
but as far as I can tell they only cover leave-one-out cross-validation (my technical Russian isn't all it could be ;o).