Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
sach ky » sac ky, sach y, sach ty
thuc xa » thuc xay, tuc xa, thuc ha
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: tu sach ky nang ma hoi. hieu van nam ((thuc xa) or (thuc va)) hanh tai ((cua tre) OR (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. hieu van nam ((thuc xa) OR (thuc va)) hanh tai ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ma hoi. hieu van nam ((thuc xa) or (thuc va)) hanh tai ((cua tre) OR (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu van nam ((thuc xa) or (thuc va)) hanh tai ((cua tre) OR (cuu tre))*.