Power Query / retrieve many queries from different files in another XL file

I have 30 xl files in one folder. Each xl file contains 1 query called Sales. As the format of the Sales source varies queries are different, however the outputs of these queries are the same.
I would like to append all data resulting of the queries in an other query in an other XL files.
How can I call a query which is in another file ?
if I write Excel.Workbook(), I can see the tab but not queries...
(I could retrieve the queries in each file and then append... but it will be really heavy and I think we might find another solution...)