PrefaceJajuga, Krzysztof; Locarek-Junge, Hermann; Orłowski, Lucjan T.; Staehr, KarstenContemporary Trends and Challenges in Finance : proceedings from the 4th Wroclaw International Conference in Finance2019 / p. v-vii https://link.springer.com/content/pdf/bfm%3A978-3-030-15581-0%2F1.pdf Conference proceeding at Scopus Article at Scopus