61845
The hydraulic ram principle has been used in some proposals for exploiting wave power , one of which was discussed as long ago as 1931 by Hanns Günther in his book " In hundert Jahren " .
 Hanns Günther
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Hanns Günther