Basic concepts of flexbox – https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Flexible_Box_Layout/Basic_Concepts_of_Flexbox
A Complete Guide to Flexbox – https://css-tricks.com/snippets/css/a-guide-to-flexbox/
CSS Flexbox Course – https://www.youtube.com/watch?v=-Wlt8NRtOpo
The Ultimate CSS3 Flexbox Tutorial – Colt’s Code Camp – https://www.youtube.com/watch?v=qZv-rNx0jEA
Should I use Grid or Flexbox? – https://rachelandrew.co.uk/archives/2016/03/30/should-i-use-grid-or-flexbox/
Quick! What’s the Difference Between Flexbox and Grid? – https://css-tricks.com/quick-whats-the-difference-between-flexbox-and-grid/
Вёрстка на Flexbox в CSS. Полный справочник – https://medium.com/@stasonmars/вёрстка-на-flexbox-в-css-полный-справочник-e26662cf87e0
Нетривиальная расстановка элементов на flexbox без media-запросов – https://habr.com/ru/post/473186/
How Flexbox works — explained with big, colorful, animated gifs – https://medium.com/free-code-camp/an-animated-guide-to-flexbox-d280cf6afc35
Размер flex-элемента (свойство flex: flex-grow, flex-shrink, flex-basis) – http://shpargalkablog.ru/2016/05/flex.html
Flexbox examples – меню – https://vahro.ru/other/flexbox-examples-menyu/
Flexbox examples – адаптивная страница – https://vahro.ru/other/flexbox-examples-page/
Колонки для списков – https://vahro.ru/other/kolonki-dlya-spiskov/#flex