Dulcie Holland theory books

[OliverH]

After WAY too long of letting it slide, I've decided to get my theory learning back on track. I dug out a couple of old Dulcie Holland Musicianship books (grades 1 and 2) and got stuck into them. I've now finished the grade 1 book (last time I got on a theory kick I got about 1/3 of the way through it) and about half of the way through the grade 2 book.

My intention is to do all the way up to grade 7 and perhaps do the AMEB music exams - even though it is unnecessary from a performance standpoint, I may want to teach at some point and I'm sure it would be useful.

The question I'm posing is this: I only have the grade 1 and 2 musicianship books and I'm looking for grade 3-7 books (2nd hand or whatever I can get) but when I Google for the books I find a number of different ones all by Dulcie Holland -
* "Musicianship"
* "Master Your Theory"
* "Practice in Musicianship"
* "Practice in Music"

There are probably others as well. I want to continue with the same line of books as I have at the moment but they are not that easy to find, and I see a lot of the other ones around. Can anyone tell me the difference between all of Dulcie Holland's different musicianship books?