I'm trying to learn Scheme as well.  I'm uncertain about why you asked for
this reference here when you could google it or ask your lecturer.  Aside
from that, I am unsure whether such a reference would do you much good
anyway.  I have a couple of Scheme references - as recommended in my
course - and to be honest, I have not found them especially helpful at all.
I can program in Delphi and there are a slew of great references around that
I can use readily.  But with Scheme, it seems you really need to get the
fundamentals of problem solving down very well before you can do much more
than tinker around.

For example, how would you go about calculating the factorial of a number
(the process) making sure to check for special cases like a zero or
negative?  If you can't answer this in your own language (mine is English)
then there is little point trying to write any code in Scheme.  I'm not
having a go at you, just sharing my own experience.

This site (and a few others) are my single best resource (aside from
frequent emails to my lecturer) on problem solving and then programming.  If
I can't do the first well I have no chance with the second.  Look at a
variety of posts (there are others in your position too) and see what people
ask and what sort of replies they receive.  I am learning a great deal just
from this alone.

Personally, trying to use Scheme has been humbling because it showed just
how poorly I understood the problem solving process.  I'm still trying my
best though ...

Good luck with your studies!