I understand people find these books to be a bit old and not an easy read. And you really need to start with volume one, since it provides a great discussion to start the reader off.
And they are not a pleasure read. But you will learn alot, and the text and their discussions are priceless and definitive.
This one is my favorite, it covers well-ordered series and ordinal numbers. Their notes are interesting and instructive Also vectors are in this volume.
For 60.00 you can get the complete set on amazon.