Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
van pham » san pham, van phan, van phat
dang xay » dang van, van xay
hieu van » hieu va, thien van, lieu va
duc van » duc va, duc tan, duc manh
duc ban » duc tan, dua ban, duc man
sach ky » sac ky, sach y, sach ty
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
cuu tre » cua tre, cau tren, cau treo
cua te » cua tu

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 ky dang xay hoi. hieu van pham ((duc ban) OR (duc van)) hanh vi ((cua te) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky dang xay hoi. hieu van pham ((duc ban) OR (duc van)) hanh vi ((cua te) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky dang xay hoi. hieu van pham ((duc ban) OR (duc van)) hanh vi ((cua te) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: thu sach ky dang xay hoi. hieu van pham ((duc ban) OR (duc van)) hanh vi ((cua te) or (cuu tre))*.