human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Source, Date, Goberman, Loera, Merkley, Neville, Novick, Obrist, Other/ Undecided
###Question: Which Loera has a Source of surveyusa, and a Date of may 16–may 18, 2008?
gpt
SELECT Loera FROM table WHERE Source = surveyusa AND Date = may 16–may 18, 2008