http://www.psychology.sunysb.edu/attachment/online/inge_origins.pdf
file:///C:/Users/sarah/Downloads/Rosmalen_et_al-2015-Journal_of_the_History_of_the_Behavioral_Sciences.pdf
https://journals.sagepub.com/doi/10.1207/S15327957PSPR0602_03
https://www.simplypsychology.org/attachment.html
https://study.com/academy/lesson/basic-trust-mistrust-erik-eriksons-theory.html
https://www.youtube.com/watch?v=QTsewNrHUHU
http://www.essentialparenting.com/2010/05/22/the-forms-of-attachment/
https://www.simplypsychology.org/mary-ainsworth.html