AUTHOR=De Pace Francesco , Manuri Federico , Sanna Andrea , Zappia Davide TITLE=Corrigendum: A Comparison Between Two Different Approaches for a Collaborative Mixed-Virtual Environment in Industrial Maintenance JOURNAL=Frontiers in Robotics and AI VOLUME=6 YEAR=2019 URL=https://www.frontiersin.org/journals/robotics-and-ai/articles/10.3389/frobt.2019.00051 DOI=10.3389/frobt.2019.00051 ISSN=2296-9144