Hoang, Tha Van, et al. “Lithofacies and Depositional Environments of the Paleogene Neogene Sediments in the Hoanh Bo Basin (Quang Ninh Province - NE Vietnam)”.
Geology, Geophysics and Environment, vol. 41, no. 4, Mar. 2016, p. 353,
https://doi.org/10.7494/geol.2015.41.4.353.