Yuan, Guowei, et al. “The Phase Behavior Study of Air-Foam Flooding in Changqing Ultra-Low Permeability Reservoirs: DOI: 10.14800 IOGR.1198”. Improved Oil and Gas Recovery, vol. 6, Jan. 2022, https://smartscitech.com/index.php/IOGR/article/view/1198.