Contribute is a synonym of Aid. Aid is related to Protection. Protection is related to Guard. 
you are likely to find Cow in/at/on Book. Cow is related to Female. Female is related to Lady. 
Contribute <--Synonym--> Aid <--RelatedTo--> Protection <--RelatedTo--> Guard 
Book <--AtLocation-- Cow <--RelatedTo--> Female <--RelatedTo--> Lady 