The following journals are tracked by Thomson Scientific (ISI): ^*

^* Services offered by Thomson Scientific (ISI) include Web of Science, Science Citation Index and Current Contents. For more information about Thomson Scientific (ISI) tracking of BioMed Central journals, see our citation tracking FAQ.

^**Unofficial Impact Factors
For journals that have not yet been tracked by Thomson Scientific (ISI) for long enough to have an Impact Factor it is nonetheless possible to calculate an unofficial Impact Factor, which we have done for some journals.

Unofficial 2006 Impact Factors were established by dividing the number of times articles published in 2004 and 2005 were cited in 2006, based on a search of the Science Citation Index database, by the number of articles published in the previous two years (2004 and 2005).

The following journals are included in MEDLINE:

Journals tracked by BIOSIS:

Most of our journals are tracked by EMBASE and Scopus (full list).

The following journals are tracked by CAS:

The following journals are tracked by CABI:

Selected articles from the following journals are made available by Medscape:

'Journals tracked by Zoological Record:

'Journals tracked by Cinahl: