Zudilin, Wadim Max Planck Institute for Mathematics, Max Planck Society;
zudilin_non-quadraticity_oa_2009.pdf (Any fulltext), 316KB
Krattenthaler, C., Rochev, I., Väänänen, K., & Zudilin, W. (2009). On the non-quadraticity of values of the q-exponential function and related $q$-series. Acta Arithmetica, 136(3), 243-269. doi:10.4064/aa136-3-4.