Is there any Reliable Chart Source

I Have been researching to see how well Queen Absolute Greatest Has Done. On Wiki apparently AG has charted #3 in the UK and then I look at the official UK Chart and all of the albums are compilations and Absolute Greatest is nowhere to be seen. And other chart websites all have different positions than each other, for example, NZ Website says AG did not Chart and on another Wensite AG charted at no.9.

In the UK the AG album entered the official album chart at Number 3.

The album is number 4 in this weeks album chart having sold 77,607 copies of Absolute Greatest last week.