You may be interested in, but are not required to read, some of Guy Steele's papers on lambda. They contain some strong juju, so be sure to give them some time if you want to learn from them.
http://library.readscheme.org/page1.html
If you're interested in language research, and you never read these papers, you're not serious about languages.
The entire site is a gold mine of interesting papers on all aspects of programming language research. Likewise, the weblog Lambda the Ultimate may provide some further readings of interest.