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The current Ridley Park Station was built by the Pennsylvania Railroad as a replacement for a much more elaborate station house which was built over the tracks by the Philadelphia , Wilmington and Baltimore Railroad during the 19th Century .
 Ridley, Pennsylvania Railroad, Philadelphia , Wilmington and Baltimore Railroad
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Ridley, Pennsylvania Railroad, Philadelphia , Wilmington and Baltimore Railroad