Amendments to patent laws. Hearings before the committee on Patents, House of Representatives, Seventy-sixth Congress, third session, on H. R. 8441, a bill to afford greater protection to the purchaser of patent rights, H. R. 8442 , a bill to prohibit proof of acts done by an inventor in foreign countries, H. R. 844, a bill to permit the assignee of an application for letters patent to make certain supplemental applications, H. R. 9384, a bill to simplify the practice in cases where a patent is or may be in part valid and in part invalid, H. R. 9386 ... H. R. 9388 ... May 9 and 16, 1940