General search engines are a great starting point for a search, because they cover every subject. They do have some disadvantages:
The four major general search engines are:
ERIC (access)
Sociological Abstracts (access)
PhilPapers (access)
Linguistics and Language Behavior Abstracts (LLBA) (access)
Rechtsorde.nl (access)
Overton (access)
OECD iLibrary (access)
Sociaal en Cultureel Planbureau (access)
Centraal Bureau voor de Statistiek (access)
Check the list of all search engines available at Utrecht University, arranged by discipline.