Perhaps you should try some spelling variations:
thien van » thi van
thu sach » tu sach, thuat sach, thuoc sach
mai khoi » mai khoa, tai khoa, cac khoi
hieu van » hieu va, lieu va, hieu ve
sach ky » sac ky, sach y, sach ty
mai hoi » dai hoi, lai hoi, mai doi
cac dat » cac dan, cai dat, cac dai
va tinh » may tinh
tinh va » tich va, trinh van, trinh vat
va cua » va chua, via cua, ca cua

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