Perhaps you should try some spelling variations:
doan manh » doan minh, hoang manh, tran manh
nam thuc » nam thuoc, am thuc, nam thu
dan manh » dang manh, van manh, day manh
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
ky lang » ky dang, ky tang, tay lang
so viet » hoc viet
ve nam » he nam, va nam, le nam
vai so » dai so, tai so, va so

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((ky lang) OR (ky nang)) xa hoi. hieu ve nam thuc ((dan manh) or (doan manh)) vai so viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky nang)) xa hoi. hieu ve nam thuc ((dan manh) OR (doan manh)) vai so viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) OR (ky nang)) xa hoi. hieu ve nam thuc ((dan manh) or (doan manh)) vai so viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) OR (ky nang)) xa hoi. hieu ve nam thuc ((dan manh) or (doan manh)) vai so viet*.