https://www.aft.org/sites/default/files/periodicals/TheEarlyCatastrophe.pdf
The 30 Million Word Gap by Age 3. By Betty hart and Todd R. Risley.
https://www.aft.org/sites/default/files/periodicals/TheEarlyCatastrophe.pdf
The 30 Million Word Gap by Age 3. By Betty hart and Todd R. Risley.