Sorensen 
Work in Tibet [PDF ebook] 
China Inland Mission

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. There is this to be said however. Under the Chinese administration, Christian missionaries were allowed to itinerate and settle west of Tatsienlu, whereas before the power of the lamas was broken by China, such a thing was almost impossible.