Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dua tren » dung tren
sach ty » sach y, sach tu, sach thu
xang ma » tang ma, nang ma, sang ma
hieu va » lieu va, hieu qua
cac toc » cac toi, cac nuoc, cac thoi
cuu tre » cau tren, cau treo
cua tre » cua te, cua triet, cua thep
toc co » hoc co, tuc co
co tao » co lao, co ta, co bao

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty xang ma hoa. hieu va cac toc co tao va ((cuu tre) or (((cua tre) OR (dua tren))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty xang ma hoa. hieu va cac toc co tao va ((cuu tre) OR (((cua tre) OR (dua tren)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty xang ma hoa. hieu va cac toc co tao va ((cuu tre) or (((cua tre) OR (dua tren))))".
• Adding a wildcard symbol may retrieve word variants: toc sach ty xang ma hoa. hieu va cac toc co tao va ((cuu tre) or (((cua tre) OR (dua tren))))*.