:::::::: "Fertility and intelligence" is a recognized field of study in the sense that it has been written about for a long time (since Galton, probably) and lots of people have studied itit was more or less the original motivation for eugenics, after all. The Lynn article would of course deal with only those of his works that are about "national IQs". They comprise IQ and the Wealth of Nations, IQ and Global Inequality, Race Differences in Intelligence, and The Global Bell Curve, plus a bunch of journal articles. There's much overlap between those four articles, and all of the books discuss both national and racial differences in IQ. Student assessment studies include mostly only OECD countries, while the reviews of Wicherts et al. concern only sub-Saharan Africa. 

 :::::::: This article may be challenged by some on the basis of WP:POVFORK and WP:N, but we'll see. Meanwhile, I would suggest using Harvard-style citations in this article.