Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
manh vai » manh hai, manh va, manh khai
dan manh » dang manh, doan manh, van manh
thuc dan » thuc hanh, hoc dan, thuc vat
nam thuc » nam thuoc, am thuc, nam thu
hieu va » lieu va, hieu qua
vai cua » dai cua, hai cua, lai cua
tu sach » thu sach, te sach, tu cach
hieu ve » hieu van
su sach » so sach, vu sach
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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) or (su sach)) ky nang o hoi. ((hieu ve) OR (hieu va)) nam thuc dan manh vai cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang o hoi. ((hieu ve) OR (hieu va)) nam thuc dan manh vai cua viet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang o hoi. ((hieu ve) OR (hieu va)) nam thuc dan manh vai cua viet*".