5Miranda P M Meuwissen, Annet G J Velthuis, Henk Hogeveen,et al. Technical and economic considerations about traceability and certification in livestock production chains [ M ]//New approa- ches to food safety economics. Wageningen: Kluwer Academic Publishers ,2003:41.
6Gabriele Jahn, Matthias Schramm, Achim Spiller. The reliability of certification:quality labels as a consumer policy tool [ J ]. J Consum Policy ,2005,28:53.