Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
nam thuc » nam thuoc, am thuc, nam thu
cau tren » cu tren, dau tren, ca tren
sach thu » sach thue, sach thieu, sach tham
lang xa » lang ha, dang xay, lang van
sach ty » sach y, sach tu, xach tay
hanh va » hang va, hanh vi
cuu tre » cua tre, cau treo
va nam » van nam, ha nam, va nay

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 thu)) lang xa hoi. lieu va nam thuc vat hanh va ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach ty) OR (sach thu)) lang xa hoi. lieu va nam thuc vat hanh va ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach ty) or (sach thu)) lang xa hoi. lieu va nam thuc vat hanh va ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: toc ((sach ty) or (sach thu)) lang xa hoi. lieu va nam thuc vat hanh va ((cuu tre) OR (cau tren))*.