Zhang, X., Tang, S., Zhao, Y., Wang, G., Zheng, H., & Zhao, B. (2017). Cold Hard E-Cash: Friends and Vendors in the Venmo Digital Payments System. Proceedings of the International AAAI Conference on Web and Social Media, 11(1), 387-396. https://doi.org/10.1609/icwsm.v11i1.14873