Before revision: For example, the invention of the polymerase chain reaction (PCR) is generally attributed to Kary Mullis, who came up with the concept in 1983, but the process of development of PCR into the revolutionary technology it became by the early 1990s took years of work by , making "who invented PCR?"
After revision: For exampleothers at Cetus Corp.—and the basic components of the system had been known since the 1960s, DNA synthesis work of Har Gobind Khorana— the invention of the polymerase chain reaction (PCR) is generally attributed to Kary Mullis, who came up with the concept in 1983, but the process of development of PCR into the revolutionary technology it became by the early 1990s took years of work by , making "who invented PCR?"