Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
va thanh » gia thanh, ban thanh, le thanh
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
van cac » van cau, van bac, dan cac
van hac » van hoc, van ha, van hai
va tinh » may tinh
doi cua » dai cua, hoi cua
ma hoi » mai hoi, xa hoi, ma hoa

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 ma hoi. hieu ((van cac) or (van hac)) dat ((va thanh) or (va tinh)) doi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang ma hoi. hieu ((van cac) OR (van hac)) dat ((va thanh) OR (va tinh)) doi cua vat.
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang ma hoi. hieu ((van cac) or (van hac)) dat ((va thanh) or (va tinh)) doi cua vat*.