Perhaps you should try some spelling variations:
mai khoi » mai khoa, tai khoa, dai khoa
van dung » van dong, xay dung
cac khoi » cac thoi, cac khoan, cach thoi
cam duc » cam xuc, cao duc, pham duc
tai cuu » tai cuc, tai buu, tai cua
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
ky lang » ky nang, ky dang, ky tang
cuu tre » cua tre, cau tren, cau treo
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky lang ((mai khoi) or (cac khoi)). hieu ve cam duc ((van dung) OR (tin dung)) tai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky lang ((mai khoi) OR (cac khoi)). hieu ve cam duc ((van dung) OR (tin dung)) tai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky lang ((mai khoi) or (cac khoi)). hieu ve cam duc ((van dung) OR (tin dung)) tai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang ((mai khoi) or (cac khoi)). hieu ve cam duc ((van dung) OR (tin dung)) tai cuu tre*.