Skoog, L., Humla, S., Axelsson, M., Frost, M., Norman, A., Nordenskjöld, B., & Wallgren, A. (1987). Estrogen Receptor Levels and Survival of Breast Cancer Patients: A study on patients participating in randomized trials of adjuvant therapy. Acta Oncologica, 26(2), 95–100. https://doi.org/10.3109/02841868709091747