In the Service of the 13th and 14th Dalai Lamas: Choegyal Nyima Lhundrup Kashopa, by Jamyang Choegyal Kasho

Untold stories from Tibet:
There is probably no personality in modern (pre 1959) Tibetan politics more colourful or controversial than Kashopa Choegyal Nyima. Most major histories of modern Tibet mention him, some like shakapba favourably others like Goldstein in less flattering terms.
In spite of his lenghty and contetious political career Kashopa has, unfortunately, not received more in-depth attention from historians and scholars, which is a pity as he was quit deeply involved in some of the most consquential events of modern Tibetan history: the Lungshar conspiracy, the imprisonment of Gedun Chopel, the Sera War, and more. One scholar has gone so far to note "that Kashopa's presence is felt in every aspect of Tibet's secret history."
Jamyang Norbu, exile writes and essayist