Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US06/939,647external-prioritypatent/US4814014A/en
Priority claimed from US07/121,898external-prioritypatent/US4960465A/en
Application filed by Grace W R & CofiledCriticalGrace W R & Co
Application grantedgrantedCritical
Publication of ATE102904T1publicationCriticalpatent/ATE102904T1/de