Data Analysis Expressions (DAX) Courses
DataCamp Using DAX throughout PowerBI to create robust data scenarios
Coursera Project Network via Coursera Excel Today - Power Pivot Tables
Learnit Training via YouTube Introducción a DAX en Power BI
Coursera Project Network via Coursera Pragmatic Self-Service BI with PowerPivot for Excel
Pluralsight Organizational BI with SSAS 2012 Tabular - Intermediate
Pluralsight