Xinyi Huang Yi Mu Willy Susilo Wei Wu Yang Xiang Further Observations on Optimistic Fair Exchange Protocols in the Multi-user Setting. 124-141 2010 Public Key Cryptography http://dx.doi.org/10.1007/978-3-642-13013-7_8 conf/pkc/2010 db/conf/pkc/pkc2010.html#HuangMSWX10