The Godfather of the 30-15 intermittent fitness test has made some articles available.
Buchheit, M., Simpson, B.M., Peltola, E., and Mendez-Villanueva, A. Assessing maximal sprinting speed in highly trained young soccer players. Int J Sports Physiol Perform 7: 76-78, 2011.
Buchheit, M., Mendez-Villanueva, A., Delhomel, G., Brughelli, M., and Ahmaidi, S. Improving repeated sprint ability in young elite soccer players: repeated shuttle sprints vs. explosive strength training. J. Strength. Cond. Res. 24: 2715-2722, 2010.
Buchheit, M., Mendez-Villanueva, A., Quod, M.J., Poulos, N., and Bourdon, P. Determinants of the variability of heart rate measures during a competitive period in young soccer players. Europ. J. Appl. Physiol. 109: 869-878, 2010.
....and many more!
The articles are accessible through Martin Buchheits dropbox HERE.