Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cao hoi » cau hoi, co hoi, cao hoc
cac dat » cai dat, cac dai, cac hat
cac dac » cac dai, cac bac, cac tac
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 ty nang cao hoi. hieu van ((((cac dat) OR (cac dac))) or (cac dan)) va tinh va cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty nang cao hoi. hieu van ((((cac dat) OR (cac dac))) OR (cac dan)) va tinh va cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ty nang cao hoi. hieu van ((((cac dat) OR (cac dac))) or (cac dan)) va tinh va cua vat".
• Adding a wildcard symbol may retrieve word variants: thu sach ty nang cao hoi. hieu van ((((cac dat) OR (cac dac))) or (cac dan)) va tinh va cua vat*.