Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
ky tang » ky nang, ky dang, kho tang
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
va danh » va dan, va hanh, dia danh
va dinh » van dinh, va kinh, va tinh
ky sang » ky nang, ky dang, duy sang
vai cau » va cau, van cau, vai cac
ve cam » ve cham, ve cac, va cam

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 sang) or (ky tang)) mai hoi. hieu ve cam xuc ((va danh) OR (va dinh)) vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ky sang) OR (ky tang)) mai hoi. hieu ve cam xuc ((va danh) OR (va dinh)) vai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((ky sang) or (ky tang)) mai hoi. hieu ve cam xuc ((va danh) OR (va dinh)) vai cau tren".
• Adding a wildcard symbol may retrieve word variants: thu sach ((ky sang) or (ky tang)) mai hoi. hieu ve cam xuc ((va danh) OR (va dinh)) vai cau tren*.