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
sang ma » tang ma, sang tao, mang may
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, nang cao, mang may
hoc van » hoc dan, hoc va, hoc vat
va chua » vua chua, ca chua, va chu
te sach » toc sach
va cua » via cua, ca cua, ma 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 ((nang ma) or (sang ma)) hoa. hieu qua cham hoc van hanh ((va cua) OR (va chua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((nang ma) OR (sang ma)) hoa. hieu qua cham hoc van hanh ((va cua) OR (va chua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty ((nang ma) or (sang ma)) hoa. hieu qua cham hoc van hanh ((va cua) OR (va chua)) tre".
• Adding a wildcard symbol may retrieve word variants: te sach ty ((nang ma) or (sang ma)) hoa. hieu qua cham hoc van hanh ((va cua) OR (va chua)) tre*.