Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dua tren » dung tren
nang ma » tang ma, sang ma, nang cao
nam xua » nam cua, nam mua, nam qua
va hanh » van hanh, va thanh, va danh
sac ky » sai ky
ma hoi » mai hoi, xa hoi, ma hoa
xua va » xuat va, vua va, sua va
vi dua » vi du, vi dum, vi lua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sac ky) OR (cac ky)) nang ma hoi. hieu van nam xua va hanh vi dua tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sac ky) OR (cac ky)) nang ma hoi. hieu van nam xua va hanh vi dua tren".
• Adding a wildcard symbol may retrieve word variants: su ((sac ky) OR (cac ky)) nang ma hoi. hieu van nam xua va hanh vi dua tren*.