Electronic Bible commentary advice

[Sammy Boy]

Hi everyone,

A good friend of mine has asked me this question:

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I'm looking to buy a commentary for the bible and want your thoughts on it. I actually prefer free electronic versions, especially on mobile.

I am currently using the iPhone, and soon going to try out Android.
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As I do not have an iPhone or similar current-gen mobile phone, I was wondering if anyone here could give some advice to my friend?

Thanks!