| 4 November 1889 |
|
Notes exchanged between Great Britain and Bulgaria, establishing a Provisional Commercial Agreement between the two Countries. |
| 31 October 1893 |
|
Notes Exchange between Great Britain and Bulgaria , prolonging the Commercial Arrangement between the two Countries of 1889 to the 31st December 1894/12th January 1895 |
| 7 May 1921 |
|
Exchange of Notes with Bulgaria to control exports of Narcotics from the United Kingdom |
| 27 November 1921 |
|
Exchange of Notes to control the Export of Narcotics from the United Kingdom |