Use to search for abstracts, citations, journal
articles.
Here are the key ones:
Astrophysics
Data System (ADS) – The big kahuna.
A database of abstracts but has some full text. Not the easiest interface
to use. Patience is a virtue. See ADS
Quick Tips.
INSPEC
– Can be easier to search than ADS. Good for a topic-based search.
Pretty comprehensive - really. Try it.
Web
of Science – good for tracking citations and sometimes finding
older (pre-1970) materials.