Locating Age-Appropriate Books for High Ability Learners

I came across this great chat article about finding age-appropriate books for high ability learners.  

In this article they start off stating the following:
"Locating age-appropriate books for high ability learners can prove difficult  for several reasons. Asynchronous development may mean that a very young child could comprehend reading material well beyond what may be considered appropriate for their age... interest levels and sensitivities also play important roles when finding appropriate yet challenging books for these children. Jo Freitag ...commented that material deemed appropriate for a child’s chronological age might be considered too simplistic and unsatisfying to the child."

At the end of the article there are a few dozen worthwhile links to help parents who are struggling with this issue.