<s>
Citebase	B-Application
Search	O
was	O
an	O
experimental	O
,	O
semi-autonomous	O
citation	O
index	O
for	O
free	O
,	O
online	O
research	O
literature	O
created	O
at	O
the	O
University	O
of	O
Southampton	O
as	O
part	O
of	O
the	O
Open	O
Citation	O
Project	O
.	O
</s>
<s>
It	O
harvested	O
open	O
access	O
e-prints	O
(	O
most	O
author	O
self-archived	O
)	O
from	O
OAI-PMH	O
compliant	O
archives	O
,	O
parses	O
and	O
links	O
their	O
references	O
and	O
indexes	O
the	O
metadata	O
in	O
a	O
Xapian-based	O
search	B-Application
engine	I-Application
.	O
</s>
<s>
Citebase	B-Application
went	O
live	O
in	O
2005	O
and	O
ceased	O
operation	O
in	O
2013	O
.	O
</s>
<s>
More	O
than	O
three-quarters	O
of	O
the	O
papers	O
indexed	O
were	O
author	O
self-archived	O
in	O
the	O
ArXiv	O
archive	O
,	O
which	O
includes	O
physics	O
,	O
maths	O
and	O
computer	B-General_Concept
science	I-General_Concept
.	O
</s>
