Exact solution for unsteady free convection flow of Casson fluid in vertical channelMohamad Ahmad Qushairi, Jiann Lim Yeou, Sharidan Shafie, Ilyas Khan and Zulkhibri IsmailMATEC Web Conf., 189 (2018) 01007DOI: https://doi.org/10.1051/matecconf/201818901007