Perhaps you should try some spelling variations:
hanh thai » nhanh thai, hinh thai, hanh tai
thai cua » than cua, tai cuc, tri cua
xang dau » hang dau
luoc van » luoc can, luoc va, luot van
luc van » luu van, duc van, luc va
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach kem
hieu ve » hieu va, hieu van
dau hoi » cau hoi, dai hoi, dan hoi
sach ty » sach y, sach tu, sach thu
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: su ((sach ky) or (sach ty)) xang dau hoi. hieu ve cam ((luc van) OR (luoc van)) hanh thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) xang dau hoi. hieu ve cam ((luc van) OR (luoc van)) hanh thai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sach ty)) xang dau hoi. hieu ve cam ((luc van) OR (luoc van)) hanh thai cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach ty)) xang dau hoi. hieu ve cam ((luc van) OR (luoc van)) hanh thai cua tre*.