Yan, K.-K. & Gerstein, M. (2011). The Spread of Scientific Information: Insights from the Web Usage Statistics in PLoS Article-Level Metrics. PLoS ONE, 6, e19917. doi: 10.1371/journal.pone.0019917

Walker, D., Xie, H., Yan, K.-K. & Maslov, S. (2007). Ranking scientific publications using a model of network traffic. Journal of Statistical Mechanics: Theory and Experiment, 2007, P06010.