1. Andrews, G.E., Askey, R., Roy, R.: Special Functions. Cambridge University, Cambridge (1999)
2. Bailey, W.N.: Generalized Hypergeometric Series. Stechert-Hafner Service Agency, New York (1964)
3. Kato, M.: Funkcialaj Ekvacioj 51:221–243 (2008)
4. Discussion about the first surprising identity, http://math.stackexchange.com/q/2123298/44121 (2017)
5. Vidunas, R.: A generalization of Clausens identity, available at http://www.arxiv.org/abs/0906.1862 (2009)