Perhaps you should try some spelling variations:
hanh than » hanh han, hanh nhan, hanh phan
nang cai » nang cao, nang tai, nang can
nang cap » nang cao, nang cham, nang phap
cua viet » ca viet, cua vat, cua dieu
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
cao hoc » co hoc, cho hoc, chat hoc
va hanh » van hanh, va thanh, va danh
va cao » va cac, va co, va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky ((nang cai) or (nang cap)) hoi. lieu va cao hoc va hanh than ((cua viet) OR (hoa viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky ((nang cai) OR (nang cap)) hoi. lieu va cao hoc va hanh than ((cua viet) OR (hoa viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky ((nang cai) or (nang cap)) hoi. lieu va cao hoc va hanh than ((cua viet) OR (hoa viet))".
• Adding a wildcard symbol may retrieve word variants: vu sach ky ((nang cai) or (nang cap)) hoi. lieu va cao hoc va hanh than ((cua viet) OR (hoa viet))*.