Perhaps you should try some spelling variations:
dung tren » dung trong, dung trung
thu sach » tu sach, thuat sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
duc van » duc va, duc tan, duc manh
ve pham » vi pham, v pham, ve phan
hieu ve » hieu va, hieu van
tang xa » trang xa, tang ma, lang xa
ty tang » tay tang, ty xang, ty hang
te sach » toc sach
cuu tre » cua tre, cau tren, cau treo

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (te sach)) ty tang xa hoi. hieu ve pham duc van hanh vi ((dung tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (te sach)) ty tang xa hoi. hieu ve pham duc van hanh vi ((dung tren) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (te sach)) ty tang xa hoi. hieu ve pham duc van hanh vi ((dung tren) or (cuu tre))*.