Reference CUSIP to german security identification number WKN?

Question

If I know the CUSIP of any security or financial instrument, how can I find out, which german WKN or ISIN is the corresponding key for this CUSIP ?

Answer 1

According to http://en.wikipedia.org/wiki/ISIN

You can formulate an ISIN from a CUSIP by -

In North America the NNA is the CUSIP organization, meaning that CUSIPs can easily be converted into ISINs by adding the US or CA country code to the beginning of the existing CUSIP code and adding an additional check digit at the end.

The site above contains the method for calculating the check digit at the end.

There is a fee-based service here for look-up at http://www.cusip.com/

You can get CUSIP's here http://activequote.fidelity.com/mmnet/SymLookup.phtml

You can look-up WKN's here by company name (search box to the left)

I'm sorry that I didn't find any free resources that will convert CUSIP's to ISIN's or WKN's