Perhaps you should try some spelling variations:
sach ky » sac ky, sach ty, sach kem
hieu ve » hieu va, hieu van
co viet » so viet, o viet, hoc viet
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
ve cac » va cac, vien cac
tuc va » thuc va, truc va, tuc xa
vi co » vi con, voi co, vi mo

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach ky) or (sach y)) nang ma hoi. hieu ve cac ((duc va) or (tuc va)) hanh vi co viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sach y)) nang ma hoi. hieu ve cac ((duc va) OR (tuc va)) hanh vi co viet.
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) or (sach y)) nang ma hoi. hieu ve cac ((duc va) or (tuc va)) hanh vi co viet*.