Encyclopedia of Language and Linguistics (online) by 
International Encyclopedia of Linguistics (online) by 
Language and Linguistics: the key concepts (online) by 
Mapping Applied Linguistics: a guide for students and practitioners (online) by Linguistics and Language Behaviour Abstracts (LLBA)
LLBA is a key database for linguistics research. It covers international journals in linguistics, language behaviour and related disciplines.
Bibliography of Linguistics Literature
Citations for research articles in linguistics.
MLA International Bibliography (Modern Languages Association)
The major database for world literature, covering all areas of modern literatures, languages, folklore, and linguistics. Coverage includes literature from all over the world—Africa, Asia, Australia, Europe, and North and South America.
PsychInfo
Psychology research that includes some linguistics-related content.
Sociological Abstracts
Research in the social sciences and includes some linguistics-related content.
