4d Precis, gist S???A??
16d Domed buildings to project the night sky ?ENI?????
17d Copying the text ?RAN???I????
76d Business deals ??A??A???O?S
113a Three-way T????A?????
The obvious answer to 16d would seem to be the plural of 'planetarium', which can be either 'planetariums' or planetaria', but that would require you to check quite a few letters!