Strunk's
Elements of Style was originally a self-published "little book" of forty-three pages, according to E. B. White in the Third Edition. It was written in 1918, privately printed in 1919, and received a general printing in 1920. According to Wikipedia, that first book is in the public domain (even in the U. S. which has virtually no public domain) and is freely downloadable. It received a retitled update by the original author and his editor in 1935. White came on board in 1959, after Strunk's death in 1946. (Neither Strunk nor White have anything to do with the Fourth and it seems to have nothing to do with the proper English language.)
White says Strunk's book was "seven rules of usage, eleven principles of composition, a few matters of form, and a list of words and expressions commonly misused..." For White's edition (so-called "First"), he added an almost twenty page fifth chapter on "An Approach to Style (With a List of Reminders)" and presumably made other minor alterations for it and the Second Edition. The Third ultimately ballooned the original chapters to sixty-five paperback pages (the "balloons" is a joke as I don't know what sort of pages the original forty-three were which, themselves, had become fifty-two by the first professional publication). As White un-Strunkishly says, the Third Edition
has been refurbished with words and expressions of a recent vintage; four rules of usage have been added to Chapter I. Fresh examples have been added to some of the rules and principles, amplification has reared its head in a few places in the text where I felt an assault could successfully be made on the bastions of its brevity, and in general the book has received a thorough overhaul--to correct errors, delete bewhiskered entries, and enliven the argument."
Passive voice! Flowery phrases! Poor sequence! Write "I added four rules of usage to Chapter I and fresh examples to Chapters II and III. Generally, I corrected errors, replaced a few old things with new, enlivened arguments and, at times, sacrificed brevity for clarity," fifty times on the blackboard!
Anyway, White's changes were accepted to the point that it's generally called "Strunk & White's" so I agree with
@dask but you're probably okay with the original (though, if you have no problems with digital books, you could return the copy your shop sent you and read it for free while using the money and space for one of the newer editions).
