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The other articles in the NL chapter of the Handbook include a historical sketch of machine translation from one language to another, which was the subject of the very earliest ideas about processing language with computers; technical articles on some of the grammars and parsing techniques that AI researchers have used in their programs; and an article on text generation, the creation of sentences by the program. Finally, there are several articles describing the NL programs themselves: the early systems of the 1960s and the major research projects of the last decade, including Wilks'S machine translation system, Winograd's SHRDLU, Woods's LUNAR, Schank's MARGIE, SAM, and PAM, and Hendrix's LIFER. Two other chapters of the Handbook are especially relevant to NL research. Speech understanding research attempts to build computer interfaces that understand spoken language. In the 197Os, speech and natural language understanding research were often closely linked.