  In this paper we show an application of the Minimum Spanning Tree (MST)
clustering method to the high-energy gamma-ray sky observed at energies higher
than 10 GeV in 6.3 years by the Fermi-Large Area Telescope. We report the
detection of 19 new high-energy gamma-ray clusters with good selection
parameters whose centroid coordinates were found matching the positions of
known BL Lac objects in the 5th Edition of the Roma-BZCAT catalogue. A brief
summary of the properties of these sources is presented.
