Article History
Received: 14 August 2018
Accepted: 24 September 2018
First Online: 26 September 2018
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standard.
: Parents of the participated children had been informed about the study aims and detailed procedures and gave written consent for their children participation in the study. The study was approved by the ethical research committee at Minia University.