参考文献:
BOEHRINGER INGELHEIM INTERNATIONAL GMBH HOFFMANN, Matthias BISCHOFF, Daniel DAHMANN, Georg KLICIC, Jasna SCHAENZLE, Gerhard WOLLIN, Stefan Ludwig Michael CONVERS-REIGNIER, Serge Gaston EAST, Stephen Peter MARLIN, Frederic Jacques McCARTHY, Clive SCOTT, John Patent: US2/29949 A, 2 Location in patent: Paragraph 25 26 27