Perhaps you should try some spelling variations:
cham duc » pham duc, cham soc, pham duy
hieu van » thien van, lieu va, hieu ve
su sach » so sach, vu sach
nang ma » tang ma, nang cao, mang may
tinh te » kinh te, tinh tu, tinh he
sang ma » tang ma, sang tao, mang may
va tinh » may tinh
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
te cua » tue cua, le cua, de cua
cua te » cua tu

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 ky ((nang ma) OR (sang ma)) hoi. ((hieu va) or (hieu van)) cham duc va tinh te cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang ma) OR (sang ma)) hoi. ((hieu va) OR (hieu van)) cham duc va tinh te cua te*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang ma) OR (sang ma)) hoi. ((hieu va) or (hieu van)) cham duc va tinh te cua te*".