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In 1903 , H. G. Wells published the short story " The Land Ironclads , " positing indomitable war machines that would bring a new age of land warfare , the way steam-powered ironclad warships had ended the age of sail .
 H. G. Wells, The Land Ironclads
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:
 H. G. Wells, The Land Ironclads