https://www.thehopeline.com/topics/friendship/
https://psychcentral.com/lib/turning-acquaintances-into-friends/
https://www.psychologytoday.com/blog/anxiety-files/201702/living-loneliness
https://www.psychologytoday.com/blog/the-gen-y-guide/201702/why-millennials-are-lonely
http://www.lifehack.org/articles/communication/11-reasons-why-you-dont-have-many-friends.html
sources