A recent article that describes the meaning and power of the HoliSurface^® system:

Less is more: from van der Rohe to the 4-channel system for the efficient and holistic analysis of surface waves. A urban case study

Dal Moro G., Moustafa S.R., Al-Arifi N., Proceedings of the GNGTS (Gruppo Nazionale Geofisica della Terra Solida - gngts.ogs.trieste.it) congress (17-19 November 2015 - Trieste, Italy).