Note that it is available a bit cheaper, too:
This particular book was always rare. It was basically the bible of ancient LISP implementation techniques (70s and earlier). Though, it did not use standard Lisp s-expressions for code, but an algebraic notation that's sometimes used in older books. Generally the content is of high quality. It was published in 1978. Generally if you wanted to know how to implement LISP way back then, you've surely looked at this book.
The book became less important in the 80s, when Lisp started to use lexical binding (Common Lisp in 1984), object-oriented subsystems (Flavors, CLOS), new machine architectures (Lisp Machines, RISC, parallel/concurrent systems, ...).
And then there are the original Lambda papers:
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