Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nang tai » hang tai, tang tai, sang tai
hanh mai » hanh ma, hanh mau, hanh may
sach ky » sac ky, sach y, sach ty
tai hoi » tai khoi, dai hoi, tai hai
hieu va » lieu va, hieu qua
va cham » va chat, va tham
luc va » tuc va, loc va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang tai hoi. hieu va cham ((luc va) or (duc va)) hanh mai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang tai hoi. hieu va cham ((luc va) OR (duc va)) hanh mai va thiet.
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang tai hoi. hieu va cham ((luc va) or (duc va)) hanh mai va thiet*.