2005 (originally) / 2011 (Taylor & Francis e-Library edition), Philipp Strazny (ed.), Encyclopedia of Linguistics: Volume 1 & 2: A-Z, Fitzroy Dearborn (an imprint of the Taylor & Francis Group), p. 688, section Middle English:
Early Middle English usually covers the time from the mid eleventh to the mid thirteen centuries. [...] The Central Middle English period is [...] Late Middle English is the time during and after Chaucer's life (born c. 1340—1346, died 1400), up to the introduction of printing. (Caxton brought out the first printed edition of The Canterbury tales in 1478.) It was during the Late Middle English period that the pronunciation changed in a complex process commonly referred to as the Great Vowel Shift.
