Perhaps you should try some spelling variations:
hanh hanh » hanh han, xanh hanh, nhanh thanh
toc sach » hoc sach, doc sach, thuoc sach
duc hanh » duc thanh, duc anh, du hanh
va trien » va truyen, va thiet, va tuyen
sach ty » sach y, sach tu, sach thu
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
van cao » van bao, van hao, van cau
vi va » vi van, vai va, vu va

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 ty ((nang xa) or (lang xa)) hoi. hieu ((van cao) OR (van dao)) duc hanh hanh vi va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((nang xa) OR (lang xa)) hoi. hieu ((van cao) OR (van dao)) duc hanh hanh vi va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty ((nang xa) or (lang xa)) hoi. hieu ((van cao) OR (van dao)) duc hanh hanh vi va trien".
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((nang xa) or (lang xa)) hoi. hieu ((van cao) OR (van dao)) duc hanh hanh vi va trien*.