Perhaps you should try some spelling variations:
luat ngan » cua ngan, luat dan
cau tren » cu tren, dau tren, ca tren
luc nhan » luc nhat, cu nhan, tue nhan
sach ty » sach y, sach tu, sach thu
hang vi » hang va, hanh vi, hang di
tu sach » thu sach, su sach, te sach
ty nang » ky nang, ty xang, ty hang
vi cau » va cau, ve cau, di cau
va dao » ca dao
x hoi » xa hoi, o hoi, x ho

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 ty nang x hoi. hieu ((va dau) OR (va dao)) ((luc nhan) or (luat ngan)) hang vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang x hoi. hieu ((va dau) OR (va dao)) ((luc nhan) OR (luat ngan)) hang vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang x hoi. hieu ((va dau) OR (va dao)) ((luc nhan) or (luat ngan)) hang vi cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang x hoi. hieu ((va dau) OR (va dao)) ((luc nhan) or (luat ngan)) hang vi cau tren*.