Nottegar, A., Veronese, N., Senthil, M., Roumen, R., Stubbs, B., Choi, A., Verheuvel, N., Solmi, M., Pea, A., Capelli, P., Fassan, M., Sergi, G., Manzato, E., Maruzzo, M., Bagante, F., Koç, M., Eryilmaz, M., Bria, E., Carbognin, L., Bonetti, F., Barbareschi, M., & Luchini, C. (n.d.). extra-nodal extension of sentinel lymph node metastasis is a marker of poor prognosis in breast cancer patients: A systematic review and an exploratory meta-analysis. European journal of surgical oncology, 42(7), 919–925. http://access.bl.uk/ark:/81055/vdc_100034056562.0x000046