Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
tu cach » tu cac
ky lang » ky nang, ky dang, ky tang
lang ha » long ha
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
duc van » duc va, duc manh, duc phan
tuan va » toan va, luan va, quan va
cua tre » cua te, cuu tre, cua triet
ha hoi » hoa hoi, ha noi, xa hoi
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 cach) or (thu sach)) ky lang ha hoi. hieu ve pham ((duc van) OR (duc tan)) tuan va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (thu sach)) ky lang ha hoi. hieu ve pham ((duc van) OR (duc tan)) tuan va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (thu sach)) ky lang ha hoi. hieu ve pham ((duc van) OR (duc tan)) tuan va cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (thu sach)) ky lang ha hoi. hieu ve pham ((duc van) OR (duc tan)) tuan va cua tre*.