Perhaps you should try some spelling variations:
ung tren » dung tren, muong tren, trung tren
khai ung » thai vung, khac tung, kham xung
dan khai » dang khai, van khai, dang khoi
cau tuc » cau truc, cau tu, cau luc
su sach » vu sach
so sach » so sanh, bo sach, co sach
mai hoi » mai khoi, dai hoi, lai hoi
ma hoi » xa hoi, ma hoa, me hoi
va cau » van cau, va cac, va dau
y nang » ky nang, ly nang, v nang
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau

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) or (so sach)) y nang ((ma hoi) OR (mai hoi)). lieu va cau tuc va dan khai ung tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) y nang ((ma hoi) OR (mai hoi)). lieu va cau tuc va dan khai ung tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) y nang ((ma hoi) OR (mai hoi)). lieu va cau tuc va dan khai ung tren*".