You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "How many Grand Slam titles were won by the defending champion of the 1981 US Open - Women's Doubles?" whose answer is 39.
Each document should contain about 30 words, and these documents should contain useful information.

Query: Martina Navratilova Grand Slam titles
Useful Output:

Doc 1: Over a spectacular career that has spanned four decades, Martina won an unprecedented 59 Grand Slam titles, including a record 9 Wimbledon singles championships
Doc 2: Roll of honour. 18 grand slam singles titles. Australian Open: 1981, 1983, 1985. French Open: 1982, 1984. Wimbledon: 1978, 1979, 1982, 1983
Doc 3: Making Olympic debut in 2004 · Winner of 18 singles, 31 doubles and nine Grand Slam titles · At age 47 is oldest Olympic tennis player, eclipsing mark set at 1924
Doc 4: Grand Slam singles finals: 32 (18–14)​​ By winning the 1983 US Open title, Navratilova completed the career Grand Slam, becoming only the seventh woman in
Doc 5: Widely considered among the greatest tennis players of all time, Navratilova won 18 Grand Slam singles titles, 31 major women's doubles titles, and 10 major