The Persistence of Early Childhood Maturity: International Evidence of Long-Run Age Effects by Kelly Bedard & Elizabeth Dhuey, The Quarterly Journal of Economics 

When Should a Kid Start Kindergarten? by Elizabeth Weil, New York Times Magazine

Summer Birth Date Children: Kindergarten Entrance Age and Academic Achievement by Sandra L. Crosser, The Journal of Educational Research (Vol. 84 | N. 3)

When is the Right Age to Start Kindergarten? by Anne Guignon, Education World

Starting school at seven ‘can boost pupils’ reading skills by Graeme Paton, The Telegraph

Pupil Age at School Entrance – How Many are Ready for Success? by James Uphoff & June Gilmore