Perhaps you should try some spelling variations:
sach thue » sach thieu, sach tham, cach thuc
sach thu » sach thieu, sach tham, cach thuc
nam dan » nam dinh
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
cac ho » cac hop, cac hoc, cac co
dan va » doan va, dan ca, ban va
va cua » va chua, via cua, ca cua
cua te » cua tu
cac o » cac co, cac bo, cac oi

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: te ((sach thu) OR (sach thue)) nang ma hoi. hieu va ((cac o) OR (cac ho)) nam dan va cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach thu) or (sach thue)) nang ma hoi. hieu va ((cac o) OR (cac ho)) nam dan va cua te~".
• Adding a wildcard symbol may retrieve word variants: te ((sach thu) or (sach thue)) nang ma hoi. hieu va ((cac o) OR (cac ho)) nam dan va cua te*.