Perhaps you should try some spelling variations:
thieu nien » thien nhien
nien cac » vien cac, dien cac, bien cac
su triet » su viet, su tien, ve triet
hanh tai » thanh tai, hang tai, han tai
va hanh » van hanh, va thanh, va danh
cac duc » cac du, cao duc, cac dac
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa

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 xa) or (nang ma)) hoi. thieu nien cac duc va hanh tai ((su triet) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. thieu nien cac duc va hanh tai ((su triet) OR (va thiet)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang ma)) hoi. thieu nien cac duc va hanh tai ((su triet) or (va thiet))*.