Popplewell 1995, p. 218 Popplewell, Richard James (1995). Intelligence and Imperial defence : British Intelligence and the defence of the Indian Empire, 1904-24. Frank Cass. ISBN9780714645803. OCLC316027333.
Popplewell 1995, p. 220 Popplewell, Richard James (1995). Intelligence and Imperial defence : British Intelligence and the defence of the Indian Empire, 1904-24. Frank Cass. ISBN9780714645803. OCLC316027333.