Perhaps you should try some spelling variations:
cham hoc » cham soc, chat hoc, cham hoi
van hanh » van thanh, ban hanh, van anh
hanh lai » hanh lam, hanh tai, thanh lap
te sach » toc sach
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
hieu va » lieu va, hieu qua
va cham » va chat, va tham
hoc van » hoc dan, hoc va, hoc vat
lai cua » dai cua, hai cua, lai chau
cua tre » cua te, cuu tre, cua triet

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 ((nang ma) or (sang ma)) hoa. hieu va cham hoc van hanh lai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((nang ma) OR (sang ma)) hoa. hieu va cham hoc van hanh lai cua tre.
• Adding a wildcard symbol may retrieve word variants: te sach ty ((nang ma) or (sang ma)) hoa. hieu va cham hoc van hanh lai cua tre*.