Nwajei, Godwin E. 2002. “HEAVY METAL CONCENTRATION IN MARINE SEDIMENTS AND VEGETATION ( CALTHA PALUSTRVIS ) FROM RIVER RAMOS IN BAYELSA AND DELTA STATES OF NIGERIA”. Biological Sciences - PJSIR 45 (2):111-13. https://v2.pjsir.org/index.php/biological-sciences/article/view/1765.