Map of Sikkim.
Dehra Dún :  Survey of India, 
1906.
"Prepared specially for the Bengal Government from an original based on sheet No. 7 N.W. N.E.T. Frontier. 3rd edition".
Print nos. No. D.13. S.1. 24-04-06. 100 D.3. S.1. 12-3-07. 100 D.183. S.1. 13-10-09. 300.
Reg. No. 246-S.06.