Reference is related to Name. Name is related to Mathematics. Mathematics is related to Study. Study is related to Psychology. 
Scent is related to Candle. you are likely to find Candle in/at/on Shelf. 
Reference <--RelatedTo--> Name <--RelatedTo--> Mathematics <--RelatedTo--> Study <--RelatedTo--> Psychology 
Scent <--RelatedTo--> Candle --AtLocation--> Shelf 