Official is related to Legitimate. Legitimate is a synonym of Natural. Natural is a synonym of Characteristic. Characteristic is related to Typical. 
Science is related to Course. Course is related to Map. you are likely to find Legend in/at/on Map. 
Official <--RelatedTo--> Legitimate <--Synonym--> Natural <--Synonym--> Characteristic <--RelatedTo--> Typical 
Science <--RelatedTo--> Course <--RelatedTo--> Map <--AtLocation-- Legend 