Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
hoc sac » hoc sach, hoc cac, hoc mac
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
cam duc » cam xuc, cao duc, pham duc
va dinh » van dinh, va kinh, va tinh
dinh va » dinh van, dinh ve, tinh va
sac ky » cac ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa
va cua » va chua, via cua, ca cua
cua cu » cua chu, cua cau, cua su

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sac ky nang ma hoi. ((hieu va) or (hieu van)) cam duc va dinh va cua cu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sac ky nang ma hoi. ((hieu va) OR (hieu van)) cam duc va dinh va cua cu.
• Adding a wildcard symbol may retrieve word variants: hoc sac ky nang ma hoi. ((hieu va) or (hieu van)) cam duc va dinh va cua cu*.