The main source of information is Flexbox Specification. We have a lot of great tutorials and courses, related to flexboxes. For practice I use CodePen, Bitbucket and CodePen. For more information about React and Flexboxes, check this list below:https://dev.to/llorentegerman/simple-layouts-with-flexbox-in-react-55kfhttps://www.npmjs.com/flexbox-grid/ or https://ant.design/ (it have layouts, that using flexboxes)