Referencias

http://www.laifi.com/laifi.php?id_laifi=1134&idC=13608#

http://idademediaied.blogspot.com.br/2012/09/economia-medieval.html

https://br.answers.yahoo.com/question/index?qid=20110811055137AAD8KRZ

http://aepocadomedievo.blogspot.com.br/2012/05/economia-medieval.html