1993 B. Tsirelson, "About Yor's problem"
Unpublished report, initially intended for communication among co-authors (Dubins, Feldman, Smorodinsky, Tsirelson); but it appears to be sometimes cited in the 21st century (M.Emery and W.Schachermayer; S.Laurent; G.Ceillier, C.Leuridan).
Full text:

1. Parametrizations.
2. Non-standard σ-fields: formulations.
3. Non-standard σ-fields: proofs.
4. Non-standard σ-fields: an equivalent measure.
5. An equivalent measure: proofs.
6. Supplement: from discrete to continuous.
7. Another proof of a standardness theorem.
8. A strengthening of the standardness theorem.