Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
va thanh » gia thanh, ban thanh, va tinh
cuu tre » cua tre, cau treo
truc va » thuc va, thuc vat, trung va
sach ky » sach y, sach ty, sach kem
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
ma hoi » mai hoi, xa hoi, ma hoa
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 hoi. hieu van cau truc va thanh tai ((cuu tre) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang ma hoi. hieu van cau truc va thanh tai ((cuu tre) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) nang ma hoi. hieu van cau truc va thanh tai ((cuu tre) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang ma hoi. hieu van cau truc va thanh tai ((cuu tre) OR (cau tren))*.