Country code: +222
Yellow Pages with listings of over 1,800 businesses in Mauritania.
Multicountry business directory - type in both what you're looking for and where (Mauritania) - needs both search boxes filled in to complete the lookup. Some results don't have telephone numbers but the ones at the top of the page are more likely to. Click on the name of the company you're looking for and this will bring up a map as well.
Business directory for Arabic speaking countries; other countries are available via the drop down list. Search via keyword or category. Results include telephone numbers, website and address.