Andersen, J., and H. S. Poulsen. “Relationship Between Estrogen Receptor Status in the Primary Tumor and Its Regional and Distant Metastases: An Immunohistochemical Study in Human Breast Cancer”. Acta Oncologica, vol. 27, no. 6, Jan. 1988, pp. 761-5, doi:10.3109/02841868809091782.