Perhaps you should try some spelling variations:
delay tomography » ray tomography, beam tomography, array tomography
early telegraph » mails telegraph, early typography, early tomography
delay telegraph » solar telegraph, aerial telegraph
der telegraph » der telegraphen, der telegraphie, _ telegraph

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((early telegraph) OR (((((delay telegraph) OR (delay tomography))) OR (der telegraph)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((early telegraph) or (((((delay telegraph) OR (delay tomography))) or (der telegraph))))".
• Adding a wildcard symbol may retrieve word variants: ((early telegraph) or (((((delay telegraph) OR (delay tomography))) or (der telegraph))))*.