Perhaps you should try some spelling variations:
thien van » thi van
van hanh » van thanh, ban hanh, van anh
thi thuy » thi thu
cua tre » cua te, cuu tre, cua triet
hanh va » hang va, hanh vi
ha thuy » thu thuy
tang ma » mang may, tang van
xac ky » cac ky, sac ky, bac ky
va cua » va chua, via cua, ca cua
su xac » pu xac, su cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: su xac ky ((nang x) or (tang ma)) hoi. thien van ((ha thuy) OR (thi thuy)) van hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su xac ky ((nang x) OR (tang ma)) hoi. thien van ((ha thuy) OR (thi thuy)) van hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su xac ky ((nang x) or (tang ma)) hoi. thien van ((ha thuy) OR (thi thuy)) van hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: su xac ky ((nang x) or (tang ma)) hoi. thien van ((ha thuy) OR (thi thuy)) van hanh va cua tre*.