Keyword "OPUKA" in:

Physical parametres of Turonian marly silicites and their relationship to the mineral composition
Šrámek,J., volume 38, 2005 (GRR for 2004), pages 147–149
pdf (0.08 MB)

Stone of Gothic Pieta from Magdeburg (Germany)
Šrámek,J., volume 37, 2004 (GRR for 2003), pages 162–163
pdf (0.89 MB)