6Juan BAS. Derivatives of alpha- or beta-mercaptopropionylamidoacetic acid and therapeutic compositions which include them as active principles [ P ]. EP :0086757,1983-08-24.
7Mita I, Toshioka N, Yamamoto S. Mercaptopropionic acid derivatives[ P]. US :3246025,1966-04-12.
8Rabjohn N. Organic syntheses collective [ M ]. Vol 4, New York: John Wiley, 1963. 924-927.
9Vogel Al. A texbook of practical organic chemistry[ M]. 4th ed. London: Longman , 1978.530.
10Mita I,Toshioka N ,Yamamoto S. Improvements in or relating to mercaptopropionyl glycines and deriva-tives thereof[ P]. GB: 1023003 ,1966-03-16.