Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
cua triet » cua viet, su triet, va triet
hieu van » hieu va, thien van, lieu va
va thanh » gia thanh, ban thanh, va tinh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ro » nang co, nang ho, nang ra
cau duc » cao duc, cau luc, cau truc
chu duc » thu duc, chua duoc, cuu duoc

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 x) or (nang ro)) hoi. hieu van ((cau duc) OR (chu duc)) va thanh dai cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang x) OR (nang ro)) hoi. hieu van ((cau duc) OR (chu duc)) va thanh dai cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang x) or (nang ro)) hoi. hieu van ((cau duc) OR (chu duc)) va thanh dai cua triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang x) or (nang ro)) hoi. hieu van ((cau duc) OR (chu duc)) va thanh dai cua triet*.