Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
va triet » va thiet, va trien, ve triet
va thanh » gia thanh, ban thanh, va tinh
sach ky » sac ky, sach y, sach ty
chu duc » thu duc, chua duoc, cuu duoc
cau duc » cao duc, cau luc, cau truc
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
nang ro » nang co, nang ho, nang ra
nang o » nang co, nang ho, nang x
dai va » mai 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 ky ((nang o) or (nang ro)) hoi. hieu va ((cau duc) OR (chu duc)) va thanh dai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang o) OR (nang ro)) hoi. hieu va ((cau duc) OR (chu duc)) va thanh dai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang o) or (nang ro)) hoi. hieu va ((cau duc) OR (chu duc)) va thanh dai va triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang o) or (nang ro)) hoi. hieu va ((cau duc) OR (chu duc)) va thanh dai va triet*.