Amusingly, I had the old "Numerical Recipes" before there were versions for the different languages. Since I was writing in BASIC and then Pascal, I had no hope but to re-write the code myself anyway, and I couldn't afford to update when the new editions came out.

Not too long ago, a colleague asked me if I had a good code for linear regression, and I sent him a copy of the page from my undergraduate data analysis textbook, which had it in FORTRAN IV.