I suggest to add footnotes as an offer for further reading, if the journal you are writing for allows them. If your target journal does not, this answer may not be applicable to you.
Citing articles is possible, but: Usually one cites only sources that are contributing to the own scientific work, sources that changed the authors mind on something, that the author argues about, that the author judge to be relevant.
If you know a cite-able source that gives proof to your statement, than provide it with your usual citing style (APA, LNI, whatever), but if you just list examples, I suggest you to offer the sources (e.g. web addresses) as further reading in footnotes.
In any case web documents are tricky to cite, because they can change over time. This makes them not the best sources for scientific citation. You can lower the risk of changing web documents by using a web preservation service like WebCite. See footnote 1 below as an example.
Your example could look like this:
Advanced web data extraction systems offer the possibility for the user to define and execute Web wrappers by means of interactive graphical users interfaces (GUI) [Aut15] (e.g. Denodo1, Kapowtech2, Lixto3 and Mozenda4).
Footnotes (same page):
1 http://www.denodo.com/ checked on 2015-07-08, archived at http://www.webcitation.org/shortlink
[Aut15] Author Examply 2015 - "On Web data extraction systems" in Paper xyz