Robert W. (Pennsylvania State University, USA) Schrauf & Kees (Groningen University, the Netherlands) de Bot 
Language Development Over the Lifespan [PDF ebook] 

Language Development Over the Lifespan is a reference resource for those conducting research on language development and the aging process, and a supplementary textbook for courses in applied linguistics/bilingualism programs that focus on language attrition/aging and adult literacy development in second languages. It offers an integrative approach to language development that examines changes in language over a lifetime, organized by different theoretical perspectives, which are presented by well-known international scholars.