Combine data in three separate data sources

Hi

I have three separate excel files, with some duplicated columns and some unique; the rows may appear in one, two or all three files (in total there are >200 rows / about 80 are unique).  For reference the column headers for each sheet are shown below.

I would like to create a table (???) showing ALL columns from the three files and to merge the information;  but to not duplicate the rows (e.g. a row that appears on both Sheet 1 and Sheet 3 would contain the same information in the first five columns - but the 'Revenue 3' column needs joining with the 'Date' cells in Sheet 1) - the aim is to have all data showing for a particular reference.  I'd appreciate your help - I have been going round in circles with this one ;)