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Additionally , he wrote a two-volume history of the Irish Guards , his son 's regiment , published in 1923 and seen as one of the finest examples of regimental history .
 organization: Irish Guards
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 organization: Irish Guards