Perhaps you should try some spelling variations:
hang tai » hang va, dung tai
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
tai duc » tai cuc, mai duc, tai du
va hang » van hang, va nang, va lang
duc tre » duoc tren, duc tien
nang ma » tang ma, sang ma, mang may
ve cac » va cac, vien cac
ve cam » ve cham, va cam, ve cai

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky ((nang ma) or (nang cao)) hoi. hieu ((ve cam) OR (ve cac)) duc va hang tai duc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky ((nang ma) OR (nang cao)) hoi. hieu ((ve cam) OR (ve cac)) duc va hang tai duc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky ((nang ma) or (nang cao)) hoi. hieu ((ve cam) OR (ve cac)) duc va hang tai duc tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ky ((nang ma) or (nang cao)) hoi. hieu ((ve cam) OR (ve cac)) duc va hang tai duc tre*.