In the original version of this article (Nguyen van yen et al. Reference Nguyen van yen, Waidmann, Klein, Farge and Schneider2018), the copyright statement incorrectly indicated that it had been transferred to Cambridge University Press. The authors retain the copyright of this work. The copyright line has been updated in the original to the following:
© The Authors 2018
The publisher apologises to the authors for this mistake.