Best resources on the Scandinavian Nf6-line?

If you mean 1.e4 d5 2.exd5 Nf6, that's pretty much the main line, because Qxd5 leads to a knee-jerk Nc3, which gains a tempo and develops a piece.

Main line? All books seems to be devoted to Qxd5

I'd say Qxd5 is the main line, when playing white against the Scandinavian I see this a lot more than Nf6.

There is a book called : Selby Anderson - CenterCounterDefense The Portuguese Variation. 1997. It is mainly about the portuguese variation, but also briefly covers the others. But I guess there are others...

I tried to order that one from 44 Baker St some time ago but it seems to be OUP.

I have written the blog post on this particular opening:
http://blog.chess.com/vincaslt/why-i-stoppend-playing-scandinavian-2-nf6