Table schema:
CREATE TABLE table_name_73 (month VARCHAR, _year VARCHAR, sunk_by_aircraft VARCHAR, sunk_by_warship_or_raider VARCHAR)

Question: What is the month and year less than 106005 were sunk by aircraft and 61857 were sunk by warship or raider?
SQL: SELECT month, _year FROM table_name_73 WHERE sunk_by_aircraft < 106005 AND sunk_by_warship_or_raider = 61857