Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vu sach » vu bach, su sach, vu khach
duoc va » nuoc va, duc va, duoc ma
cua tre » cua te, cua triet, dua tren
danh di » danh du, xanh di, danh dien
cuu tre » cau tren, cau treo
sach ky » sac ky, sach y, sach ty
tuoc va » thuoc va, nuoc va, tuc va
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang ma hoi. hieu vien bach ((tuoc va) OR (duoc va)) danh di ((cua tre) OR (cuu tre))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang ma hoi. hieu vien bach ((tuoc va) or (duoc va)) danh di ((cua tre) OR (cuu tre))~".
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang ma hoi. hieu vien bach ((tuoc va) or (duoc va)) danh di ((cua tre) OR (cuu tre))*.