1. Abdullah MH (2001) Phreatic water extraction from shallow aquifer of a small island. PhD Thesis, Universiti Teknologi Malaysia [in Malay]
2. Abdullah MH, Musta B, Ramli MZ (1996) Groundwater quality as freshwater resource in Manukan island––a preliminary finding. In: Proceedings of geology and environmental seminar, pp 33–37. Bangi, Selangor [in Malay]
3. Abdullah MH, Mokhtar MB, Tahir S, Awaluddin A (1997a) Do tides affect water quality in the upper phreatic zone of a small oceanic island, Sipadan Island, Malaysia?. Environ Geol 29:112–117
4. Abdullah MH, Musta B, Tan MM (1997b) A preliminary geochemical study on Manukan Island, Sabah. Borneo Sci 3:43–51
5. Abdullah MH, Kassim MA, Hanapi MN (2002) Saltwater encroachment into the sandy aquifer of Manukan Island, Sabah. Borneo Sci 12:1–22