What is the volume of this article in a journal? I have this line about the article:

BioMedical Engineering OnLine 2007, 6:16 doi:10.1186/1475-925X-6-16


I think the volume is 6.
Then what is 16?

How should you correctly cite the Bibliography in Tex?

My BibTeX

%
% Published abstract
%
@ARTICLE{vladimir,
    author = {Kudriavtsev V, Polyshchuk V and Roy D L},
    title = {Heart energy signature spectrogram for cardiovascular diagnosis},
    journal = {BioMedical Engineering OnLine},
    year = {2007},
    volume = {6:16}
}


I am suspicious about the author and the volume field.
As others have already said, it's an article number. 
You can verify on the publisher's website that papers in the same volume have indeed consecutive numbers.

As far as I can tell there is no bibtex field for an article number, so you'll have to work around it. Personally I'd go for volume=6, number=16, and no page field (it's not mandatory for an @article). The publisher's own bibtex file (go on "download reference" from the article page linked above) reads VOLUME = {6},NUMBER = {1},PAGES = {16} instead; that said, publishers' bibtex files are often quite bad, don't take this for an authoritative answer.

More importantly, the formatting of the author field is wrong. It should be Kudriavtsev, V. and Polyshchuk, V. and Roy, D. L., or even better (if you know their names) Kudriavtsev, Vladimir and Polyshchuk, Vladimir and Roy, Douglas L.. Note that the correct format is surname, name or surname, n., with "and" as the author separator. What you wrote would be parsed as two authors, one with given name Polyshchuk V and surname Kudriavtsev V, and one with surname only Roy D L. Abbreviations and sorting could go wrong with such a field.

For more information on formatting .bib files, ask on http://tex.stackexchange.com.