DDD Home: www.gnu.org/software/ddd
Quicksort, CAR Hoare, April, 1962: www3.oup.co.uk/computer_journal/hdb/Volume_05/Issue_01/050010.sgm.abs.html
The Practice of Programming by Brian W. Kernighan and Rob Pike, pp. 32-34 (ISBN: 0-201-61586-X).
GDB Home: www.gnu.org/software/gdb