Which is the place where the child's cognitive development is defined in the best way?

Child cognitive development is best defined by reputable sources such as academic literature, research journals, and respected organizations specializing in child development. Key sources include books by developmental psychologists, peer-reviewed journals like “Child Development,” and websites of research institutions such as Harvard’s Center on the Developing Child. These resources provide comprehensive insights into cognitive milestones, processes, and factors influencing children’s learning and thinking abilities.