Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
hanh lai » hanh lam, hanh tai, thanh lap
doc sach » hoc sach, toc sach, nuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
thuc va » thuc vat, thuc day
doc sac » dac sac, hoc sach, toc sach
nang ma » tang ma, sang ma, nang cao
hieu vi » hieu voi, hieu va, hieu ve
ma hoi » mai hoi, xa hoi, ma hoa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((doc sac) OR (doc sach)) ky nang ma hoi. hieu vi pham ((thuc va) or (thuc dan)) hanh lai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc sac) OR (doc sach)) ky nang ma hoi. hieu vi pham ((thuc va) OR (thuc dan)) hanh lai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc sac) OR (doc sach)) ky nang ma hoi. hieu vi pham ((thuc va) or (thuc dan)) hanh lai su triet".
• Adding a wildcard symbol may retrieve word variants: ((doc sac) OR (doc sach)) ky nang ma hoi. hieu vi pham ((thuc va) or (thuc dan)) hanh lai su triet*.