Later versions of Strunk and White

Do later versions of "Strunk and White" include significant additional material compared to the free version available from Project Gutenberg?

Also, I note that some of the rules in the 1918 version appear to be out of date. E.g. to always write "to-day" with a hyphen, and to always write "anyone" as two words. Are there any other recommendations/rules in the 1918 version that are out of date?

 

Yes, I bought a copy recently and its has been updated multiple times since its first publication.

 

the fourth ed. is the latest...

 

Thanks for the comments. I'm going to wait for my copy of Self-Editing for Fiction Writers, Second Edition: How to Edit Yourself Into Print Renni Browne, Dave King to arrive. The bookseller hasn't even dispatched it yet for whatever reason. Anyhow, I'm going to wait until I get that before I decide to buy Strunk and White's latest edition. In case the former covers the quite short latter. In the meantime I'm continuing to revise the 1918 version, as I think I can work out which advice is still relevant today, and which is out of date.