Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
va thanh » gia thanh, ban thanh, va tinh
hieu van » hieu va, thien van, lieu va
dai cuu » dai cua, dai huu
truc va » thuc va, thuc vat, trung va
van cau » van dau, van hau, van chat
sach ky » sach y, sach ty, sach kem
nang ma » tang ma, sang ma, mang may
cuu tre » cua tre, cau tren, cau treo
sac ky » cac ky, sai ky

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) or (sac ky)) ((nang ma) OR (nang cao)) hoi. hieu van cau truc va thanh dai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) ((nang ma) OR (nang cao)) hoi. hieu van cau truc va thanh dai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) ((nang ma) OR (nang cao)) hoi. hieu van cau truc va thanh dai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) ((nang ma) OR (nang cao)) hoi. hieu van cau truc va thanh dai cuu tre*.