On December 23, 1947, Bardeen and Brattain were working without Shockley when they succeeded in creating a point-contact transistor that achieved amplification. By the next month, Bell Labs' patent attorneys started to work on the patent applications. Bell Labs' attorneys soon discovered that Shockley's field effect principle had been anticipated and patented in 1930 by Julius Lilienfeld, who filed his MESFET-like patent in Canada on October 22, 1925. Shockley publicly took the lion's share of the credit for the invention of transistor; this led to a deterioration of Bardeen's relationship with Shockley. Bell Labs management, however, consistently presented all three inventors as a team. Shockley eventually infuriated and alienated Bardeen and Brattain, and he essentially blocked the two from working on the junction transistor.