1. Adams CG (1970) A reconsideration of the East Indian letter classification of the tertiary. Bull Br Mus (Nat Hist) Geol 19:87–137
2. Adams CG (1984) Neogene larger foraminifera, evolutionary and geological events in the context of datum planes. In: Ikebe N, Tsuchi R (eds) Pacific Neogene datum planes. University of Tokyo Press, Tokyo, pp 47–67
3. Boudagher-Fadel MK (2002) The stratigraphical relationship between planktonic and larger benthic Foraminifera in middle Miocene to lower Pliocene carbonate facies of Sulawesi, Indonesia. Micropaleontology 48:153–176
4. Boudagher-Fadel MK, Banner FT (1999) Revision of the stratigraphic significance of the Oligo-Miocene “Letter Stages.”. Rev Micropaleontol 42:93–97
5. Cahuzac B, Poignant A (1997) Essai de biozonation de I’Oligo-Miocène dans les bassins européens à l’aide des grands foraminifères néritiques. Bull Soc Geol Fr 168:155–169