Complex sentence: Lesley's work in sociolinguistics focuses on urban and rural dialectology, language ideology and standard, and includes her most famous work studying social networks and linguistic variations in Belfast in the 1970's.
Split into simpler sentences: Lesley's work in sociolinguistics focuses on urban and rural dialectology, language ideology and standard. Perhaps Milroy's most famous work studying examined social networks and linguistic variation in Belfast in the 1970's.