Updates are available Expression of concern dated 2017-11-11

Click to view Expression of concern: https://doi.org/10.1007/s11192-017-2575-8

Retraction Retraction dated 2020-12-17

Click to view Retraction: https://doi.org/10.1007/s11192-020-03818-6

Retraction Retraction dated 2020-12-17

Click to view Retraction: https://doi.org/10.1007/s11192-020-03818-6