Since it's the inspiration for sooooo many modern writers' take on him there must be something special from that era.

ARGH!!
Something must be done with the vine's bugs. My comment was gone, again!

*Sigh* here we go again:

1. Superman Sunday strips (collected by IDW)
2. Superman # 30
3. Superman # 132
4. Superman # 141
5. Superman # 162
6. Superman # 164
7. Superman # 167
8. Superman # 170 (if LUTHOR was Superman's Father :P, probably were Morrison got the idea about Kal being a decendant of Lex. Lex trying to became Superman's father so Supes won't oppose him because he is his father is hilarious)
9. Superman # 174
10. Superman # 247 (this is where the "Must there be a Superman" concept was born, a concept favored by many writers currently)
11. Superman # 400
12. Action Comics # 300
13. Action Comics # 544
14. Kryptonite nevermore
15. Whatever Happened to the man of tomorrow

A very good way to get many of these are the Superman in the fifties/sixties etc series or Superman: The greatest stories ever told.

In what story did Morrison but that idea? I wanna read that :O

Morrison came up with the idea that Superman is a man from the future and then gave it to Millar for his Red Son.

Of course that story doesn't have anything to do with it and there is no source that Morrison is influenced from that story. I just found it very interesting considering how deep Morrison has looked into SA Supes.