Ask HN: Books for Parents of Mathematics-Loving Children?

I am wondering what books would be good to recommend to parents whose children are deeply in love with mathematics, especially if the parents themselves have only an average background in mathematics. That was my situation a decade ago, and I found some helpful books I'll mention here, but I think a lot of Hacker News participants can suggest some books that are even better. I'll be speaking to a group of parents whose children are primary-school age but already well familiar with secondary school algebra and geometry, taking an advanced mathematics summer course.

Books that I found helpful for understanding mathematics when my oldest son, a mathematics-lover, was growing up include

Concepts of Modern Mathematics by Ian Stewart (Dover reprint)

Numbers and Geometry by John Stillwell (Springer)

Vision in Elementary Mathematics by W. W. Sawyer (Dover reprint)

The Art of Problem Solving by Sandor Lehoczky and Richard Rusczyk (Art of Problem Solving)

A frequently recommended book for this need is Developing Math Talent by Susan Assouline and Ann Lupkowski-Shoplik, but I haven't made much use of that book.

What am I missing? What do you recommend?