Perhaps you should try some spelling variations:
sach ty » sach y, sach tu, sach thu
va phan » van phan, va phat, va phap
truc va » thuc va, thuc vat, trung va
tu sach » thu sach, su sach, te sach
hieu su » hieu sau, tieu su, hieu so
nang ho » nang hoc, nang co, tang ho
ty nang » ky nang, ty xang, ty hang
hieu va » lieu va, hieu qua
ho hoi » hoc hoi, hoa hoi, hoi hoi
lap su » lap du, lai su, lap so
lap tu » lap du

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 ho hoi. ((hieu su) or (hieu va)) cau truc va phan ((lap su) OR (lap tu)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ho hoi. ((hieu su) OR (hieu va)) cau truc va phan ((lap su) OR (lap tu)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ho hoi. ((hieu su) or (hieu va)) cau truc va phan ((lap su) OR (lap tu)) triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ho hoi. ((hieu su) or (hieu va)) cau truc va phan ((lap su) OR (lap tu)) triet*.