Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
trinh ve » trinh he, trinh va, trinh vi
nang hoc » nang doc, nang luc, dong hoc
hieu va » lieu va, hieu qua
tu sach » thu sach, su sach, te sach
nang ho » nang co, tang ho, nang cao
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
ve va » ve van, te va, ke va

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