9203
Many observers claimed to have determined such parallaxes , but Tycho Brahe and Giovanni Battista Riccioli concluded that they existed only in the minds of the observers , and were due to instrumental and personal errors .
 Tycho Brahe, Giovanni Battista Riccioli
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Tycho Brahe, Giovanni Battista Riccioli