Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cham hoc » cham soc, chat hoc, cham hoi
qua cham » qua hai, qua cac, va cham
sach ty » sach y, sach thu, xach tay
hanh va » hang va, hanh vi
hoc van » hoc dan, hoc va, hoc vat
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
sach tu » sach thu, cach tu, sach uu
cua tre » cua te, cuu tre, cua triet
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: te ((sach ty) or (sach tu)) ((nang ma) or (tang ma)) hoa. hieu qua cham hoc van hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ty) OR (sach tu)) ((nang ma) OR (tang ma)) hoa. hieu qua cham hoc van hanh va cua tre.
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) or (sach tu)) ((nang ma) or (tang ma)) hoa. hieu qua cham hoc van hanh va cua tre*.