Perhaps you should try some spelling variations:
phan duc » pham duc, phan tu, phan dau
va hanh » van hanh, va thanh, va danh
hieu ke » hieu kem, chieu ke, hieu ky
tu sach » thu sach, su sach, te sach
tu nong » tu dong, tu cong, tu tong
tu nang » tru nang, tu nano, tu lang
ke phan » ve phan, kenh phan, ke thang
oi su » ki su, vi su
ve su » va su

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 ((tu nang) OR (tu nong)) xa hoi. hieu ke phan duc va hanh ((oi su) or (ve su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((tu nang) OR (tu nong)) xa hoi. hieu ke phan duc va hanh ((oi su) OR (ve su)) triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((tu nang) OR (tu nong)) xa hoi. hieu ke phan duc va hanh ((oi su) or (ve su)) triet*".