Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
dua tren » dung tren
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
tang ma » mang may, tang van
van cau » van dau, van hau, van chat
cau luc » cau truc, cau phuc
luc van » luoc van, luu van, duc van
sach ky » sac ky, sach y, sach ty
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cua triet, cua thep
ky tang » ky nang, ky dang, kho tang
cuu tre » cau tren, cau treo
ma hoi » mai hoi, xa hoi, ma hoa

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 tang ma hoi. hieu van cau luc van hanh di ((((cua tre) OR (dua tren))) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky tang ma hoi. hieu van cau luc van hanh di ((((cua tre) OR (dua tren))) OR (cuu tre))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky tang ma hoi. hieu van cau luc van hanh di ((((cua tre) OR (dua tren))) or (cuu tre))*".