1. A history of lactic acid making;Benninga,1990
2. Poly(lactic acid): synthesis, structures, properties, processing, and application;Auras,2010
3. U.S. patent 5,357,035;Gruber,1994
4. U.S. patent 6,326,458;Gruber,2001
5. Polymers for biodegradable medical devices. 1. The potential of polyesters as controlled macromolecular release systems