Broker is a type of Book. Journal is a type of Book. you are likely to find Study in/at/on Journal. 
Unit is related to Country. Country is related to Economy. Sector is part of Economy. Sector is a type of Aspect. 
Broker --IsA--> Book <--IsA-- Journal <--AtLocation-- Study 
Unit <--RelatedTo--> Country <--RelatedTo--> Economy <--PartOf-- Sector --IsA--> Aspect 