Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
cau tren » cu tren, dau tren, ca tren
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky dang, ky tang, duy sang
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
vi cau » va cau, ve cau, di cau
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 nang)) mai hoi. hieu ve cam xuc ((va hanh) OR (va danh)) vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ky sang) OR (ky nang)) mai hoi. hieu ve cam xuc ((va hanh) OR (va danh)) vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((ky sang) or (ky nang)) mai hoi. hieu ve cam xuc ((va hanh) OR (va danh)) vi cau tren".
• Adding a wildcard symbol may retrieve word variants: thu sach ((ky sang) or (ky nang)) mai hoi. hieu ve cam xuc ((va hanh) OR (va danh)) vi cau tren*.