Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
cau tren » cu tren, dau tren, ca tren
thanh vi » hanh vi, thanh va, thanh ve
pham duy » pham duc
cuu tre » cua tre, cau treo
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
nang ra » nang ma, lang ra, nang va
nang ro » nang co, nang ho, nang rong
ve pham » vi pham, v pham, ve phan

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 ro) or (nang ra)) hoi. hieu ve pham duy vat thanh vi ((cuu tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang ro) OR (nang ra)) hoi. hieu ve pham duy vat thanh vi ((cuu tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang ro) or (nang ra)) hoi. hieu ve pham duy vat thanh vi ((cuu tre) or (cau tren))*.