Perhaps you should try some spelling variations:
doan manh » doan minh, hoang manh, tran manh
thu sach » tu sach, thuat sach, thuoc sach
hieu van » thien van, lieu va, hieu ve
dan manh » dang manh, van manh, day manh
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
co viet » so viet, o viet, hoc viet
x hoi » xa hoi, o hoi, x ho

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

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