Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
lang van » dang van, hoang van, giang van
tang van » dang van, hoang van, trong van
va kinh » va tinh, qua kinh
cam duc » cam xuc, cao duc, pham duc
hieu ve » hieu va
sach ty » sach y, sach tu, sach thu
cua tre » cua te, cuu tre, cua triet
te cua » tue cua, le cua, de cua

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 ((lang van) OR (tang van)) hoi. ((hieu ve) or (hieu van)) cam duc va kinh te cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((lang van) OR (tang van)) hoi. ((hieu ve) OR (hieu van)) cam duc va kinh te cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty ((lang van) OR (tang van)) hoi. ((hieu ve) or (hieu van)) cam duc va kinh te cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((lang van) OR (tang van)) hoi. ((hieu ve) or (hieu van)) cam duc va kinh te cua tre*.