Laboratorium Dźwięku Koala 2. In Gustorzyn darker shade marks bones described by excavators as belonging to human skulls, in Żerniki Górne human skulls were solely recognised basing on published figures; stone constructions were omitted. Currently, strontium Sr and oxygen O isotope analyses are the most robust and effective tools used in archaeology for mobility and geographic provenance studies [ 7 , 8 , 15 , 17 , 32 — 34 ].