1. 2011-04-01 [racket] HTDP 17.1.2; applying methodology to imperat racket-us Jay 2. 2011-03-31 [racket] HTDP 17.1.2; applying methodology to imperat racket-us Matthias Felleisen 3. 2011-03-31 [racket] HTDP 17.1.2; applying methodology to imperat racket-us Jay