Perhaps you should try some spelling variations:
hanh hanh » hanh han, xanh hanh, nhanh thanh
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
duc hanh » duc thanh, duc anh, du hanh
va triet » va thiet, ve triet, cua triet
va trien » va truyen, va thiet, va tuyen
ty nang » ty xang, ty hang, ly nang
van cao » van dao, van bao, van hao
cao duc » dao duc, cao suc, giao duc

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