Dynamic hierarchy of needs of Abraham Maslow referring to Krech, D./Crutchfield, R. S./Ballachey, E. L. (1962), Individual in society, Tokyo etc. 1962, S. 77
<a href="//commons.wikimedia.org/wiki/User:Artyl" title="User:Artyl">Philipp Guttmann</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>