Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
thu sach » tu sach, thuat sach, thuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
thuc van » thuc vat, thuc va, thuc hanh
tai cuu » tai cuc, tai buu, tai cua
cuu tre » cua tre, cau tren, cau treo
sach ty » sach y, sach tu, sach thu
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
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: thu sach ty ((nang ma) or (nang x)) hoi. hieu va nam ((thuc van) OR (thuc dan)) thanh tai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty ((nang ma) OR (nang x)) hoi. hieu va nam ((thuc van) OR (thuc dan)) thanh tai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty ((nang ma) or (nang x)) hoi. hieu va nam ((thuc van) OR (thuc dan)) thanh tai cuu tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ty ((nang ma) or (nang x)) hoi. hieu va nam ((thuc van) OR (thuc dan)) thanh tai cuu tre*.