There are only few specialised linguistic dabases such as LLBA. It is more common that linguistics can be found in more general databases covering the humanities and possibly also the social sciences.
BDSL online = Bibliographie der deutschen Sprach- und Literaturwissenschaft. References to monographs, articles in anthologies, periodicals and newspapers as well as reviews. Covers German and Dutch languages and comparative literary studies.
LLBA=Linguistics and Language Behavior Abstracts. Indexes articles, books dissertations and reviews. Covers linguistics in general. Also good coverage of minor languages.
FRANCIS = French Retrieval Automated Network for Current Information in Social and Human Sciences. Indexes mainly articles but also books, reports and dissertations. Multiple languages: 35% English, 33% French, 12% German, 5% Italian, 15% others. It is possible to search with English keywords, but French keywords, perhaps found through the index, gives a better result.
MLA=Modern Languages Association of America. References to books, articles, and reviews. Covers linguistics, comparative literary studies and folklore.