Qari, Salmai Public Economics, MPI for Tax Law and Public Finance, Max Planck Society;
http://sfb649.wiwi.hu-berlin.de/papers/pdf/SFB649DP2011-017.pdf (Any fulltext)
Qari, S., & Hofmann, D. (2011). The Law of Attraction: Bilateral Search and Horizontal Heterogeneity. SFB 649 Discussion Paper, 2011-017.