Perhaps you should try some spelling variations:
nang cau » nang cao, hang cau, nang dau
hieu van » hieu va, thien van, lieu va
hanh cat » hanh cac, hanh luat, nhanh cay
su sach » so sach, vu sach
hanh ca » hanh cac, hanh cua, hanh cad
ty nang » ky nang, ty xang, ty hang
van cau » van dau, van hau, van chat
sach ty » sach y, sach tu, sach thu
tuc va » thuc va, truc va, tuc xa
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: su sach ty nang cau hoi. hieu van cau ((duc va) or (tuc va)) ((hanh ca) or (hanh cat)) va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty nang cau hoi. hieu van cau ((duc va) OR (tuc va)) ((hanh ca) OR (hanh cat)) va thiet.
• Adding a wildcard symbol may retrieve word variants: su sach ty nang cau hoi. hieu van cau ((duc va) or (tuc va)) ((hanh ca) or (hanh cat)) va thiet*.