Independence: Why Scots Should Rule Scotland

by Alasdair Gray

Which you can buy here

(The 1992 version is more expensive and difficult to locate, try here as a starting point).

see also 'Why we should Rule ourselves' which is a great statement of modern republicanism

and

Old Scotland New Scotland

by Jeff Fallow

which is an updated version of Jeff's comic book history 'Revolting Scotland'

and can be bought here

Both of these books are excellent illuminating guides to Scottish history and also to the basic arguments for Scottish independence.  

See also the Scottish Writers Project for more information about contemporary Scots authors.

and a Scottish Writers guide from Visit Scotland here