Supercharge Power BI is a book written by Matt Allington. Matt Allington is a career data professional who has worked in the retail and consumer packaged good industries for more than 35 years. Matt is a Microsoft MVP and specializes in Power BI, Power Pivot, and Power Query. 

I find this book particularly good for people who does not know Power BI and DAX language. I started this book when I almost knew nothing about DAX language. the explanation is clear and sometimes, I felt that the instructor knew what the audience was thinking. when I have a question in my mind, he explains right away. it is an excellent introductory book for Power BI. 

It does not cover all of the more than 250 DAX functions. However, it certainly includes the basics and fundamentals, and commonly used functions such as sum, calculate, filter, all select, switch, etc. It is enough for your daily use. 

In summary, a well-written book for Power BI starters.