A royal proclamation of King Rama VI of Siam dated 23 December 1926 <a href="https://en.wikipedia.org/wiki/Common_Era" class="extiw" title="w:Common Era">CE</a>, amending details regarding provisional apprehension of criminals under the expedition treaty between Siam and Britain dated 4 March 1911 <a href="https://en.wikipedia.org/wiki/Common_Era" class="extiw" title="w:Common Era">CE</a>, as published in the Siamese  Government Gazette on 26 December 1926 <a href="https://en.wikipedia.org/wiki/Common_Era" class="extiw" title="w:Common Era">CE</a>.
Government of Siam
1926-01-26
<a rel="nofollow" class="external text" href="http://www.ratchakitcha.soc.go.th/DATA/PDF/2469/A/595.PDF">Royal Siamese Government Gazette, volume 43, part 0 A, dated 26 December 1926, pp. 595–599</a>