Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
thien van » thi van
hoc sach » hoc sinh, hoc anh
hieu van » hieu va, lieu va, hieu ve
cau tren » cu tren, dau tren, ca tren
hoc cac » hoc cao
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
va cau » van cau, va cac, va dau
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: ((hoc sach) OR (hoc cac)) ky nang x hoi. ((hieu van) or (thien van)) cham thuc va hanh va cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (hoc cac)) ky nang x hoi. ((hieu van) OR (thien van)) cham thuc va hanh va cau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) OR (hoc cac)) ky nang x hoi. ((hieu van) or (thien van)) cham thuc va hanh va cau tren*".