Perhaps you should try some spelling variations:
sach trien » sach tien, sach tren, sach thieu
trien nang » trien nong, trien mang, thien nang
va triet » va thiet, va trien, ve triet
dau tren » dau tien, dat tren, dau tieng
tu sach » thu sach, su sach, te sach
van cam » van lam, van cau, van dam
va hanh » van hanh, va thanh, va danh
nang o » nang co, nang ho, nang ro
xuc va » duc va, tuc va, luc va
o hoi » co hoi, o hoc, o hai

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