You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Let me give you an example: Category: HOMOPHONIC PAIRS 
Clue: It's a notation on a percussion store to clash
The answer to this example can be: cymbal symbol
Here is why: "Cymbal" and "symbol" both have the same pronunciations but different meanings, hence they are homophonic pairs. A symbol is the notation and a cymbal is a percussion instrument that clashes and rings.

OK. solve this:
Category: PSYCHOLOGY 
Clue: The concept of the "Oedipus Complex" was introduced in this 1899 book
Answer:
the interpretation of dreams