Pitopang R., P.J.A. Keßler, S.R. Gradstein, E. Guhardja, S.S. Tjitrosoedirdjo & H. Wiriadinata (2004). Tree Composition in Secondary Forest of Lore Lindu National Park, Central Sulawesi, Indonesia. In: G. Gerold, M. Fremerey and E. Guhardja (eds.), /Land Use, Nature Conservation and the Stability of Rainforest Margins in South Asia. /Berlin, Springer Verlag. - Schulze, C., M. Waltert, P.J.A. Keßler, R. Pitopang, Shahabuddin, D. Veddeler, M. Mühlenberg, S.R. Gradstein, C. Leuschner, I. Steffan-Dewenter & T. Tscharntke (2004). Biodiversity indicator taxa of tropical land-use systems: comparing plants, birds and insects. /Ecological Applications/ 14: 1321-1333.
Kessler, M., P.J.A. Keßler, S.R. Gradstein, K. Bach, M. Schmull & R. Pitopang (2005). Tree diversity in primary forest and different land use systems in Central Sulawesi, Indonesia. /Biodiversity and Conservation/14: 547-560. Gradstein, S.R., M. Kessler & R. Pitopang (2007). Tree species diversity relative to human land uses in tropical rain forest margins in Central Sulawesi. Pp. 321-334 /in/ Tscharntke, T., C. Leuschner, M. Zeller, E. Guhardja & A. Bidin (eds) /The stability of tropical rainforest margins, linking ecological, economic and social constraints of land use and conservation/. Springer, Berlin. Aryanti, N.S. & S.R. Gradstein (2007). Wallace’s line and the distribution of the liverworts of Sulawesi. /Cryptogamie, Bryologie/ 28: 3-14. - Steffan-Dewenter, I., M. Kessler, J. Barkmann, M. Bos, D. Buchori, S. Erasmi, H. Faust, G. Gerold, K. Glenk, S.R. Gradstein, E. Guhardja, M. Harteveld, D. Hertel, P. Höhn, M. Kappas, S. Köhler, C. Leuschner, M. Maertens, R. Marggraf, S. Migge-Kleian, J. Mogea, R. Pitopang, M. Schaefer, S. Schwarze, S.G. Sporn, A. Steingrebe, S.S. Tjitrosoedirdjo, S. Tjitrosoemito, A. Twele, R. Weber, L. Woltmann, M. Zeller & T. Tscharntke (2007). Tradeoffs between income, biodiversity, and ecosystem function during rainforest conversion and agroforestry intensification. /Proceedings of the National Academy of Sciences, USA /104: 4973-4978.
Sporn, S.G., M. Bos & S.R. Gradstein (2007). Is productivity of cacao impeded by epiphytes? An experimental approach/. Agriculture, Ecosystems & Environment /122: 490-493.