Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
thu sach » tu sach, thuoc sach, thu hoach
hieu van » hieu va, thien van, lieu va
nang ma » tang ma, sang ma, nang cao
van cac » van hac, van cau, van bac
cac dat » cac dan, cai dat, cac dai
hanh di » hanh de, hang di, danh di

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) or (thuat sach)) ky nang ma hoa. hieu van cac dat va ((hanh di) OR (hanh vi)) cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thuat sach)) ky nang ma hoa. hieu van cac dat va ((hanh di) OR (hanh vi)) cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thuat sach)) ky nang ma hoa. hieu van cac dat va ((hanh di) OR (hanh vi)) cua vat".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thuat sach)) ky nang ma hoa. hieu van cac dat va ((hanh di) OR (hanh vi)) cua vat*.