Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cua viet » ca viet, cua vat, cua dieu
hieu van » hieu va, thien van, lieu va
hanh doi » thanh doi, hanh noi, hang doi
ty nang » ky nang, ty xang, ty hang
cao hoi » cau hoi, co hoi, cao hoc
cac duc » cac du, cao duc, cac dac
sach ty » sach y, sach tu, sach thu
cac bac » cac bai, cac ban, cac cach
va hanh » van hanh, va thanh, va danh

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ty nang cao hoi. hieu van ((cac duc) or (cac bac)) va hanh doi ((cua viet) OR (hoa viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang cao hoi. hieu van ((cac duc) OR (cac bac)) va hanh doi ((cua viet) OR (hoa viet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty nang cao hoi. hieu van ((cac duc) or (cac bac)) va hanh doi ((cua viet) OR (hoa viet))".
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang cao hoi. hieu van ((cac duc) or (cac bac)) va hanh doi ((cua viet) OR (hoa viet))*.