Does anyone know what version of Gregg I've been learning?

Hi all,
Very happy to have found this resource!  I started learning recently from sheafs (excerpts) taken off the internet, and find it fascinating.   Keen to thoroughly learn the language, and think I've gone far enough to warrant picking out a proper book, but I have no idea which version of Gregg I am (half-way through) learning.  One key difference I've noticed is that the "I" sound (eg. "my" or "tie") is a big O with a small extra bit of ink on the inside.  It doesn't seem to be the anniversary edition.  Any ideas which version I am using?

(by berrymerry for everyone)