That's the best advice ever.
If I may add for the OP : always use manufacturer's and/or your company approved material and this will be more than enough to have an extensive knowledge of the aircraft. If You think on the amount of official Airbus data You can access through the web, mostly for free, there is for sure no need to invest in any sort of unofficial apps. I can add to that only one exception : you might find some very interesting booklets on the external walkaround that are based on data collected from maintenance documentation. That could be a nice to know with highly detailed colour pictures to extend Your knowledge and have a better understanding of what You're actually looking at during the exterior walkaround.