Intelligent Human Systems Integration 2021 Proceedings of the 4th International Conference on Intelligent Human Systems Integration (IHSI 2021): Integrating People and Intelligent Systems, February 22-24, 2021, Palermo, Italy - Russo, Dario; Ahram, Tareq; Karwowski, Waldemar; Di Bucchianico, Giuseppe; Taiar, Redha (Springer International Publishing, 2021)