Adni, N., Mulyadi, A. and Thamrin, T. 2021. POPULATION CONDITIONS OF ECHINOIDEA AND CORAL REEF COVERS IN PONCAN GODANG ISLAND, SIBOLGA, NORTH SUMATERA. Asian Journal of Aquatic Sciences. 4, 2 (Aug. 2021), 112-116. DOI:https://doi.org/10.31258/ajoas.4.2.112-116.