TUMUKLU, A., GUMUS, H. and SEN, S. (2010) “Role of Trace Elements in Natural Amethysts in Colouring”, Asian Journal of Chemistry, 20(5), pp. 4138–4140. Available at: https://asianpubs.org/index.php/ajchem/article/view/12735 (Accessed: 29 November 2024).