Bulgaria–United States relations to work. Bulgaria became a member of the Warsaw Pact on May 14, 1955. Though no Soviet troops were stationed on Bulgarian soil, in 1968, Zhivkov sent a Bulgarian division to join Polish, Hungarian and Soviet troops to crush a popular uprising in Prague. In 1978, the Bulgarian secret police were implicated in the assassination in London of Georgi Markov, a Bulgarian dissident who was a correspondent for the BBC World Service, Deutsche Welle radio and the U.S. sponsored Radio Free Europe. Markov was assassinated with a poisoned umbrella on September 7, Zhivkov's birthday. The rise of democratic movements across
London Buses route 7 and London Bridge station. This route disappeared later in 1916 owing to Wartime shortages, but reappeared on 30 April 1917. During the 1920s, route 7 was extended to Acton and a 7B was introduced as a Waterloo station to London Bridge, Monday to Friday peak hours only service via Holborn. On 1 December 1924, a new system of route numbering on London buses came into force under The London Traffic Act 1924. This gave the Metropolitan Police responsibility for bus operation and route numbering. Route 7 remained unchanged; the 7A was renumbered 107, and the 7B to 166. Short workings