Perhaps you should try some spelling variations:
doan manh » doan minh, hoang manh, tran manh
thu sach » tu sach, thuat sach, thuoc sach
dan manh » dang manh, van manh, day manh
hoc viet » hoc hien
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
sach ky » sac ky, sach y, sach ty
co viet » so viet, o viet, hoa 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 nam thuc ((dan manh) or (doan manh)) vai ((co viet) OR (hoc viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang x hoi. hieu van nam thuc ((dan manh) OR (doan manh)) vai ((co viet) OR (hoc viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang x hoi. hieu van nam thuc ((dan manh) or (doan manh)) vai ((co viet) OR (hoc viet))".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang x hoi. hieu van nam thuc ((dan manh) or (doan manh)) vai ((co viet) OR (hoc viet))*.