Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
van hanh » van thanh, ban hanh, van anh
sach luu » sach uu, sach luan, sach dau
hanh ki » hanh vi, hanh ky, hanh kien
xuc van » duc van, luc van, vuc van
tu sach » thu sach, su sach, te sach
nang ma » tang ma, sang ma, nang cao
nong ma » dong ma, cong ma, nong va
va cam » va cham, va cao, va cai
ki su » ky su

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach luu ((nong ma) OR (nang ma)) hoi. hieu ((va cam) or (va cac)) xuc van hanh ki su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach luu ((nong ma) OR (nang ma)) hoi. hieu ((va cam) OR (va cac)) xuc van hanh ki su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach luu ((nong ma) OR (nang ma)) hoi. hieu ((va cam) or (va cac)) xuc van hanh ki su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach luu ((nong ma) OR (nang ma)) hoi. hieu ((va cam) or (va cac)) xuc van hanh ki su triet*.