Perhaps you should try some spelling variations:
cach thoi » cac thoi, cach thuc, cach noi
van hang » van khang, van hoang, van thang
dai khoa » da khoa, tai khoa, dac khoa
duc van » duc va, duc tan, duc manh
cam duc » cam xuc, cao duc, pham duc
hieu ve » hieu va, hieu van
tu sach » thu sach, su sach, te sach
ky tang » ky nang, ky dang, kho tang
ky lang » ky nang, ky dang, tay lang
cua tre » cua te, cuu tre, cua triet
ve cam » ve cham, ve cac, va cam
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: tu sach ((ky lang) OR (ky tang)) ((dai khoa) or (cach thoi)). hieu ve cam duc van hang va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky tang)) ((dai khoa) OR (cach thoi)). hieu ve cam duc van hang va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) OR (ky tang)) ((dai khoa) or (cach thoi)). hieu ve cam duc van hang va cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) OR (ky tang)) ((dai khoa) or (cach thoi)). hieu ve cam duc van hang va cua tre*.