Katre, S. A., and A. R. Rajwade. “Resolution of the Sign Ambiguity in the Determination of the Cyclotomic Numbers of Order 4 and the Corresponding Jacobsthal Sum”. MATHEMATICA SCANDINAVICA 60 (December 1, 1987): 52–62. Accessed May 6, 2024. https://www.mscand.dk/article/view/12171.