参考文献:
BOEHRINGER INGELHEIM INTERNATIONAL GMBH EBEL, Heiner FRATTINI, Sara GIOVANNINI, Riccardo HOENKE, Christoph TRIESELMANN, Thomas TIELMANN, Patrick SCHEUERER, Stefan HOBBIE, Silke (Marie Katrin) Patent: WO/73 A, Location in patent: Page/Page column 6-7 WO /73 A