Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach thi » sach thu, sach tai, sach thieu
thi nang » thi cong, ki nang, thi hanh
hanh lai » hanh lam, hanh tai, thanh lap
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
thuc va » thuc dan, thuc day
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa

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 thi nang ma hoi. hieu va cac ((thuc va) or (thuc vat)) hanh lai ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach thi nang ma hoi. hieu va cac ((thuc va) OR (thuc vat)) hanh lai ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach thi nang ma hoi. hieu va cac ((thuc va) or (thuc vat)) hanh lai ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: toc sach thi nang ma hoi. hieu va cac ((thuc va) or (thuc vat)) hanh lai ((cua tre) OR (cuu tre))*.