SQL * Plus user's guide and reason: http://rfhs8012.fh-regensburg.de/~oracle/sqlplus/toc.html
Oracle Documentation: http://www.oracle.com/technology/documentation/index.html (Cityforest / 04110610)
Free Oracle Getting Started: http://fengyu.china.com/
Oracle e-books: http://www.newebug.com/ebook/oracle/407.SHTML
SQL Editor Tutorial http://www.princeton.edu/~storacle/sqleditor_tutorial.shtml
