Stanley A. Cook“A Pre-Massoretic Biblical Papyrus,”Proceedings of the Society of Biblical Archaeology25 (1903) 34-56and Francis C. Burkitt “The Hebrew Papyrus of the Ten Commandments” The Jewish Quarterly Review 15 (1903) 392-408. Though the two articles are dated to 1903 Burkitt had apparently seen Cook’s article before submitting his own for publication.
An opinion also cited by R.H. Charles“The Decalogue being the Warburton Lectures in Lincoln’s Inn and Westminster Abbey 1919-1923 (T & T Clark: Edinburgh 1923) ” p. xxii. On p. xxviii Charles has a cross-reference to a footnote on p. xxii where depending on Pilcher he mentions “prudential reasons” as causing this omission in the papyrus. Here Charles though he does not say so is apparently dependent on the study by Cook mentioned above f.n. 1.