Number of Business days between two date values - minus public holidays :-)

Number of Business days between two date values - minus public holidays :-)

hi
i know there is a possible way to calculate business days (mo-fr) between two date values... but has anyone tried to deduct also public holidays ..... best would be to use a public available service somewhere. second best solution would be to import a table with the holidays to a creator record.....
thank you
Lambert