select m.mnf_name FROM manufacturer as m,

					(
					  select DISTINCT n.ngt_mnf_code as mnfCode FROM negotiation as n, 
											(
											select u.usr_email as mailUser
											FROM
											user as u
											WHERE u.usr_off_code='1' AND u.usr_type='B'
											) as usrByer
										WHERE usrByer.mailUser=n.ngt_buyer_usr_code
					) as ngtMnf
					WHERE ngtMnf.mnfCode=m.mnf_code