Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban hanh » ban hang
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cua triet, dua tren
sach ky » sac ky, sach y, sach ty
van cam » van nam, van lam, van cau
nang xa » lang xa, nang ma, mang xa
cuu tre » cau tren, cau treo
cam ly » tam ly, cam ky, cam lo
ly ban » uy ban, lo ban, ly bai

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky ((nang xa) or (nang x)) hoi. hieu van cam ly ban hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((nang xa) OR (nang x)) hoi. hieu van cam ly ban hanh vi ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((nang xa) or (nang x)) hoi. hieu van cam ly ban hanh vi ((cua tre) or (cuu tre))*.