reading: Lauwaert, Maaike (2009). The Place of Play: toys and digital cultures [pdf]. Amsterdam: Amsterdam University Press. Please read Part II, section 8 ‘Brand extension and product differentiation’ pp.58-62.
(Section 7 ‘LEGO toys: from wooden blocks to plastic bricks’ pp.50-58. provides a useful history of LEGO and a thoughtful account of the bricks as material technologies so read it as well if you are interested).

suggested further reading:
Kline, Stephen. 1993. Out of the Garden: toys, TV, and children’s culture in the age of marketing. London: Verso.
Wolf, Mark J.P. (ed.) 2014. Lego Studies: examining the building blocks of a transmedial phenomenon, New York: Routledge.