Perhaps you should try some spelling variations:
thien van » thi van
cau tren » cu tren, dau tren, ca tren
thuc day » thuc dan, thuc vat
day manh » van manh, duc manh, ha manh
nam thuc » nam thuoc, am thuc, nam thu
su sach » so sach, vu sach
manh va » hanh va, anh va, minh va
hieu ve » hieu va, hieu van
va cau » van cau, va cac, va dau
su sac » su cac, su xac
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: ((su sac) OR (su sach)) ky nang x hoi. ((hieu ve) or (thien van)) nam thuc day manh va cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sac) OR (su sach)) ky nang x hoi. ((hieu ve) OR (thien van)) nam thuc day manh va cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sac) OR (su sach)) ky nang x hoi. ((hieu ve) or (thien van)) nam thuc day manh va cau tren".
• Adding a wildcard symbol may retrieve word variants: ((su sac) OR (su sach)) ky nang x hoi. ((hieu ve) or (thien van)) nam thuc day manh va cau tren*.