Analysis of the causes of false negative and false positive results of preoperative axillary ultrasound in patients with early breast cancer – a single-centre study - Nowikiewicz, Tomasz; Nowak, Adam; Wiśniewska, Magdalena; Wiśniewski, Michał; Nowikiewicz, Magdalena; Zegarski, Wojciech (Contemporary Oncology/Współczesna Onkologia, 2018)