Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
cau tren » cu tren, dau tren, ca tren
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
cau loc » hau loc, cau hoc, cau luc
sach ky » sac ky, sach y, sach ty
danh vi » hanh vi, danh di, danh va
dinh vi » dinh ve, dinh viet, dinh tri
ma hoi » mai hoi, xa hoi, ma hoa

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