Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
doan thi » dan thi, doanh tai, hoang thi
lang van » dang van, tang van, hoang van
tu cach » tu cac
ve cham » va cham, ve chat, vu cham
thi cua » thai cua, thi cuc, tri cua
va doan » va doanh, van doan, va dan
truc va » thuc va, thuc vat, trung va
cua tre » cua te, cuu tre, cua triet
van hoi » van hoa, van hoc, van hoe
ky lang » ky nang, ky dang, ky tang
ve cam » ve cac, va cam, ve cai

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 van hoi. hieu ((ve cam) OR (ve cham)) truc va doan thi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (thu sach)) ky lang van hoi. hieu ((ve cam) OR (ve cham)) truc va doan thi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu cach) or (thu sach)) ky lang van hoi. hieu ((ve cam) OR (ve cham)) truc va doan thi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (thu sach)) ky lang van hoi. hieu ((ve cam) OR (ve cham)) truc va doan thi cua tre*.