1. Broun, J.A., (1872). II. On the 26-day period of the earth’s magnetic force. Proceedings of the Royal Society of London, 20(130−138), pp. 417−425.
2. Broun, J.A. ed., (1874). Observations of magnetic declination, made at trevandrum and agustia malley in the observatories of his highness the maharajah of travancore, GCSI in the years 1852 to 1869 1. King.
3. Caldecott, J. (1837). Account of the Trevandrum Observatory. In R. Cole (Ed.), The Madras Journal of Literature and Science.
4. Kurien, P. (2009). History of Astronomical Science in Kerala. PhD Thesis, University of Kerala; Shodhganga, India.
http://hdl.handle.net/10603/71693.
5. Ratcliff, J. (2016). Travancore’s magnetic crusade: Geomagnetism and the geography of scientific production in a princely state. BJHS, 49(3), 325–352. https://doi.org/10.1017/S0007087416000340