Hi everyone,
I have found a previous post about the differences between the editions.
I pasted the link below just in case there might be someone struggling between editions like me. As I am using a 9th edition of the textbook, I was quite concerned whether I am on the right page.
http://forum.math.toronto.edu/index.php?topic=182.0
Wish it would help!

And
please add corrections if you got to check the textbooks.