Tsubak, Michiko http://orcid.org/0000-0001-9948-6503
Maeda, Yoshihiro
Article History
Received: 20 September 2019
Accepted: 13 December 2019
First Online: 28 December 2019
Compliance with ethical standards
: To the best of our knowledge, the named authors have no conflict of interest, financial or otherwise.
: This research involves human participants.
: Informed consent has been obtained from all parents of pupils included in this study.