Germany
Official starting point
Federal Statistical Office (Destatis) is the starting point for this country's official statistical sources.
Finding and recording a series
GENESIS-Online provides configurable statistical tables. The official web-service documentation is the starting point for automated access; retain the table identifier and all selected dimensions.
When a download is offered, retain the file alongside the table metadata. Check the publisher's current export options and licence; this page does not promise a particular format or API.