Markus Jakobsson Frank Thomson Leighton Silvio Micali Michael Szydlo Fractal Merkle Tree Representation and Traversal. 314-326 2003 conf/ctrsa/2003 CT-RSA http://link.springer.de/link/service/series/0558/bibs/2612/26120314.htm db/conf/ctrsa/ctrsa2003.html#JakobssonLMS03