Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
tham soc » cham soc, tham nuoc, thai son
hieu van » hieu va, thien van, lieu va
van tham » van thanh, van tuan, van chat
dang xay » dang van, van xay
lang xa » lang ha, lang van
va hanh » van hanh, va thanh, va danh
va dinh » van dinh, va kinh, va tinh
cuu tre » cua tre, cau tren, cau treo
vi cuu » vi luu, vinh cuu

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach y ((lang xa) OR (dang xay)) hoi. hieu van tham soc ((va hanh) or (va dinh)) vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach y ((lang xa) OR (dang xay)) hoi. hieu van tham soc ((va hanh) OR (va dinh)) vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach y ((lang xa) OR (dang xay)) hoi. hieu van tham soc ((va hanh) or (va dinh)) vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: hoc sach y ((lang xa) OR (dang xay)) hoi. hieu van tham soc ((va hanh) or (va dinh)) vi cuu tre*.