Even in the rarefied atmosphere of the academic journal, the apostrophe can still be a problem - check out a few random papers here and there and you'll find instances that have escaped the editorial process. Given that, it's nice to come across a clear guide to what and what not to do: How to use an apostrophe
I once sat down with a couple of Master's students and explained the whole thing to them in a very similar way and they claimed that no one had ever explained the apostrophe before - primary school, secondary school, university degree, and they had remained blissfully ignorant. Could it be that their teachers either didn't know or didn't care?
I'd only disagree with one thing - the author says, 'If in doubt, don't use an apostrophe': I'd prefer him to have said, 'If in doubt - find out!'