Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
cau thuc » cau truc, cuu thuc, can thuc
dau tren » dau tien, dat tren, dau tieng
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
danh vi » hanh vi, danh di, danh va
dinh vi » dinh ve, dinh viet, dinh tri
ve cau » ke cau, va cau, ve cac

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 ky nang ((xa hoi) or (mai hoi)). hieu ve cau thuc va ((danh vi) OR (dinh vi)) dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky nang ((xa hoi) OR (mai hoi)). hieu ve cau thuc va ((danh vi) OR (dinh vi)) dau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky nang ((xa hoi) or (mai hoi)). hieu ve cau thuc va ((danh vi) OR (dinh vi)) dau tren".
• Adding a wildcard symbol may retrieve word variants: hoc sach ky nang ((xa hoi) or (mai hoi)). hieu ve cau thuc va ((danh vi) OR (dinh vi)) dau tren*.