Programming Language: ANSI Scheme by R. Kent Dybvig, Second
Edition, 1996, is available online in its entirety. There is also an
tutorial which is the online version of the text How to Design Programs. Prof Aaby
something between a tutorial and a cheat sheet.
For a reasonable tutorial of managable length, try
tutorial by Paul R. Wilson.
For a good thin book to learn Scheme from, try
The Little Schemer.
For a book that will make your head explode with good stuff, try
Structure and Interpretation of Computer Programs.
For a more accessible text, often used in CS257, try
Scheme and the Art of Programming.