1. Multicellular spheroids. A review on cellular aggregates in cancer research;Mueller-Klieser;J Cancer Res Clin Oncol,1987
2. Cell and environment interactions in tumor microregions: the multicell spheroid model;Sutherland;Science,1988
3. Recent developments in research with human tumor spheroids;Knuechel;Cancer J,1990
4. pO2- and pH-gradients in multicellular spheroids and their relationship to cellular metabolism and radiation sensitivity of malignant human tumor cells;Görlach;Biochem Biophys Acta,1994
5. The use of human tumor cells grown in multicellular spheroid culture for designing and improving therapeutic strategies;Acker;J Theor Med,1998