Tracing technological shifts: time-series analysis of correlations between patent classes M. Maragakis, M. A. Rouni, E. Mouza, M. Kanetidis and P. Argyrakis Eur. Phys. J. Plus, 138 9 (2023) 776 Published online: 01 September 2023 DOI: 10.1140/epjp/s13360-023-04344-z