Perhaps you should try some spelling variations:
sinh thai » dinh thi
hinh thai » tinh thai, dinh thi, chinh tai
sach ky » sac ky, sach ty, sach kem
duc van » duc va, duc tan, duc manh
ve giao » te giao, viet giao, van giao
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
nang o » nang co, nang ho, nang ro
o hai » co hai, so hai, o lai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach ky) or (sach y)) nang o hai. hieu ve giao duc van ((hinh thai) OR (sinh thai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sach y)) nang o hai. hieu ve giao duc van ((hinh thai) OR (sinh thai)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) or (sach y)) nang o hai. hieu ve giao duc van ((hinh thai) OR (sinh thai)) cua tre*".