001 Django-Models-Official-Docs-
https://docs.djangoproject.com/en/1.11/topics/db/models/

002 Django-Model-Fields-Official-Docs-
https://docs.djangoproject.com/en/1.11/ref/models/fields/

002 Substituting-a-custom-User-model-Official-Docs-
https://docs.djangoproject.com/en/1.11/topics/auth/customizing/#auth-custom-user

002 models.py
https://gist.github.com/LondonAppDev/850fec3c9e1b255b7e5ba583464519cd

002 PEP-8-Guidelines
https://www.python.org/dev/peps/pep-0008/

003 normalize-email-Official-Docs-
https://docs.djangoproject.com/en/1.11/topics/auth/customizing/#django.contrib.auth.models.BaseUserManager.normalize_email

003 models.py
https://gist.github.com/LondonAppDev/7e2bd045ecaeb742a42c94168c301af3

003 PEP-8-Guidelines
https://www.python.org/dev/peps/pep-0008/

004 Official-Django-docs-for-custom-user-model-setting
https://docs.djangoproject.com/en/2.2/ref/settings/#std:setting-AUTH_USER_MODEL