Cowan, J. A., Howard, J. A., Puschmann, H., & Williams, I. D. (2007). Short N center dot center dot center dot O hydrogen bonds in the 1 : 1 adduct of 4,4 `-bipyridyl and oxalic acid. Acta Crystallographica Section E: Crystallographic Communications, 63(3), o1240-o1242. https://doi.org/10.1107/s1600536807005156