WFMW Backwards Edition - Book Recommendations for Young Boys

My Works for Me Wednesday - Backwards Edition question is what are some good books for young boys. My son is almost 6.

We just finished all our Dan Frontier books (about frontiersman, Indians, soldiers etc) - that is the kind of stuff my son loves.

So I'm looking for another very boyish series of books that he will want to keep reading. They need to be simple enough for him to read on his own - but more than just a couple of sentences on each page.

Any ideas??

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