Encyclopedia of Language and Linguistics (2nd edn.)
The publisher says its “[t]he most authoritative, up-to-date, comprehensive, and international reference source in its field” with 3,000 articles and 3,500 glossary definitions. Highly recommended!
International Encyclopedia of Linguistics (2nd edn.)
The Encyclopedia encompasses the full range of topics in linguistics,
including such areas as historical, comparative, formal, mathematical,
functional, philosophical, and sociolinguistics. Special attention is
given to interrelations within these branches of the field and to
relations of linguistics with other disciplines.
Blackwell Reference Online (Linguistics)
Up-to-date handboooks on many fields of linguistics including English
Linguistics, Historical Linguistics, Language Contact and World
Englishes.
Handbooks of Linguistics and Communication Science (HSK)
This series of HANDBOOKS OF LINGUISTICS AND COMMUNICATION SCIENCE is
designed to illuminate a field which not only includes general
linguistics and the study of linguistics as applied to specific
languages, but also covers those more recent areas which have developed
from the increasing body of research into the manifold forms of
communicative action and interaction. Volumes include Corpus
Linguistics, Contact Linguistics, Sprachgeschichte and many more.
Oxford Handbooks Online (Linguistics)
Advertised by OUP as “one of the most successful and cited series within scholarly publishing, containing in-depth, high-level articles by scholars at the top of their field and for the first time”. Full texts of 21 books covering topics from “Applied Linguistics” to “Translation Studies”.