Perhaps you should try some spelling variations:
sach thue » sach thu, sach thieu, sach tham
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
lang van » dang van, tang van, hoang van
van hoi » van hoa, van hoc, van hoe
sach ty » sach y, sach tu, sach thu
danh va » doanh va, anh va, dan va
hanh va » hang va, hanh vi
cuu tre » cua 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: toc ((sach ty) or (sach thue)) lang van hoi. hieu van nam thuc vat ((danh va) OR (hanh va)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach ty) OR (sach thue)) lang van hoi. hieu van nam thuc vat ((danh va) OR (hanh va)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach ty) or (sach thue)) lang van hoi. hieu van nam thuc vat ((danh va) OR (hanh va)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc ((sach ty) or (sach thue)) lang van hoi. hieu van nam thuc vat ((danh va) OR (hanh va)) cuu tre*.