<s>
A	O
bibliographic	B-Library
index	I-Library
is	O
a	O
bibliography	O
intended	O
to	O
help	O
find	O
a	O
publication	O
.	O
</s>
<s>
Citations	O
are	O
usually	O
listed	O
by	O
author	O
and	O
subject	O
in	O
separate	O
sections	O
,	O
or	O
in	O
a	O
single	O
alphabetical	O
sequence	O
under	O
a	O
system	O
of	O
authorized	O
headings	O
collectively	O
known	O
as	O
controlled	O
vocabulary	O
,	O
developed	O
over	O
time	O
by	O
the	O
indexing	B-Library
service	I-Library
.	O
</s>
<s>
Since	O
the	O
1970s	O
they	O
are	O
typically	O
generated	O
as	O
output	O
from	O
bibliographic	B-Library
databases	I-Library
(	O
whereas	O
earlier	O
they	O
were	O
manually	O
compiled	O
using	O
index	O
cards	O
)	O
.	O
</s>
<s>
The	O
index	O
may	O
help	O
search	O
the	O
literature	O
of	O
,	O
for	O
example	O
,	O
an	O
academic	O
field	O
or	O
discipline	O
(	O
example	O
:	O
Philosopher	B-Library
's	I-Library
Index	I-Library
)	O
,	O
to	O
works	O
of	O
a	O
specific	O
literary	O
form	O
(	O
Biography	B-Library
Index	I-Library
)	O
or	O
published	O
in	O
a	O
specific	O
format	O
(	O
Newspaper	B-Library
Abstracts	I-Library
)	O
,	O
or	O
to	O
the	O
analyzed	O
contents	O
of	O
a	O
serial	O
publication	O
(	O
New	O
York	O
Times	O
Index	O
)	O
.	O
</s>
