The Algol 60 language report appeared in May 1960, so exactly sixty years ago.
My eye was caught by this remark, a propos the careful specification of Algol 60's syntax,
> indeed many early languages were virtually defined by the action (not always predictable) of their compilers.
But they immediately qualify that with
> Unfortunately the rigour with which the syntax of ALGOL is defined does not extend to the semantics...
J. McCarthy, R. Brayton, D. Edwards, P. Fox, L. Hodes, D. Luckham, K. Maling, D. Park and S. Russell. LISP I Programmer's Manual. Computation Center and Research Laboratory of Electronics, Massachusetts Institute of Technology, March 1, 1960.
Copy 1: Computer History Museum Lot X????.200?, George Michael donation. http://bitsavers.org/pdf/mit/rle_lisp/LISP_I_Programmers_Manual_Mar60.pdf
Copy 2: Science and Technology Collection, M.I.T. Museum, Cambridge, Massachusetts, catalog number 1993.053, donated by Timothy P. Hart. Missing cover and Acknowledgements. http://www.softwarepreservation.org/projects/LISP/book/LISP%20I%20Programmers%20Manual.pdf
Copy 3: From Supplementary Materials for Oral History of Phyllis A. Fox. The History of Numerical Analysis and Scientific Computing, Society for Industrial and Applied Mathematics (SIAM). http://history.siam.org/sup/Fox_1960_LISP.pdf