CREATE TABLE table_name_61 (best_3_year_period VARCHAR(255), best_15_year_period VARCHAR(255), position VARCHAR(255))
Which best 3-year period has a best 15-year period of smyslov; kasparov, and a Position of 5?
    
SQL: SELECT best_3_year_period FROM table_name_61 WHERE best_15_year_period = "smyslov; kasparov" AND position = 5