Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
van thanh » ban thanh, van tuan
qua pham » quan pham, quy pham, qua cham
cua tre » cuu tre, cua triet, dua tren
duc van » duc va, duc tan, duc manh
sach ky » sac ky, sach y, sach kem
sach ty » sach y, sach tu, sach thu
nang o » nang co, nang ho, nang ro
cua te » cua tu
o hai » co hai, so hai, o lai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) OR (sach ty)) nang o hai. hieu qua pham duc van thanh hai ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang o hai. hieu qua pham duc van thanh hai ((cua tre) OR (cua te))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sach ty)) nang o hai. hieu qua pham duc van thanh hai ((cua tre) or (cua te))*".