Perhaps you should try some spelling variations:
viet tech » viet sach
tech nuoc » dich nuoc, sach nuoc
hieu viet » sieu viet, hieu viec, lieu viet
cua tre » cua te, cua triet, dua tren
danh di » danh du, xanh di, danh dien
va danh » va dinh, va dan, va hanh
su sach » so sach, vu sach
mai hoi » mai khoi, dai hoi, lai hoi
ly nang » ly hang, ly vang, ly quang
cuu tre » cau tren, cau treo

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