Complex sentence: A basic model often used in the period of 1950-1970 was the classification model of Webster, this model has been adapted by Milman and Wilson into a two dimensional model and was paramount in the period of 1970-1990.
Split into simpler sentences: A basic model often used in the period of 1950-1970 was the classification model of Webster. This model has been adapted by Milman and Wilson into a two dimensional model and was paramount in the period of 1970-1990.