Correction to: Phys. Perspect. https://doi.org/10.1007/s00016-019-00241-0

Dear readers,

In the original publication of this article, the author noticed some minor errors.

In the caption of Fig. 7, the name “Y. K. Hs” should be changed to “Y. K. Hsü”.

Page 5: at the end of 2nd paragraph under the Note number “16”), there is a superfluous comma (“,”) that should be deleted.

We apologize for these errors.