Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
ky sang » ky dang, ky tang, duy sang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
tuc va » thuc va, truc va, duc va
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di 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 sang) or (ky nang)) ma hoi. hieu ve cham ((tuc va) or (tuc xa)) dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky sang) OR (ky nang)) ma hoi. hieu ve cham ((tuc va) OR (tuc xa)) dan vi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky sang) or (ky nang)) ma hoi. hieu ve cham ((tuc va) or (tuc xa)) dan vi cua tre*.