Tsering Shakya, Dragon in The Land of Snows: The History of Modern Tibet since 1947, Random House, 2012, Google e-book: "Tibet had never received de jure recognition from any state; in any case such recognition would be disputed not only by Beijing but also by the nationalist regime in Taiwan.
Stephanie Roemer, The Tibetan government-in-exile: politics at large, p.32: "the Tibetans signed the so-called 'Seventeen Point Agreement', where they officially acknowledged the Chinese intentions to liberate Tibet, which meant the end of Tibet's de-facto independence."
NOTE: The exiled Tibetan government in India calls The battle the "...invasion of Tibet by the People's Liberation Army of China," see Tibet: Proving Truth From Facts. The Status of Tibet: "At the time of its invasion by troops of the People's Liberation Army of China in 1949, Tibet was an independent state in fact and by law."
Dunham, Mikel (2005). Buddha's warriors: the story of the CIA-backed Tibetan freedom fighters, the Chinese invasion, and the ultimate fall of Tibet. New Delhi: Penguin Books. pp.54–60, 62. ISBN0144001047. OCLC224529359.
Dunham, Mikel (2005). Buddha's warriors: the story of the CIA-backed Tibetan freedom fighters, the Chinese invasion, and the ultimate fall of Tibet. New Delhi: Penguin Books. p.60. ISBN0144001047. OCLC224529359.