Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
mai khoa » tai khoa, may khoa, dai khoa
danh vai » danh sai, danh va, doanh van
cham hoc » cham soc, chat hoc, cham hoi
cau tren » cu tren, dau tren, ca tren
mai hoi » mai khoi, dai hoi, lai hoi
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
va danh » va dinh, va dan, va hanh
ky sang » ky nang, ky dang, ky tang
vai cau » va cau, van cau, vai cac
hieu ve » hieu van

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 ((mai hoi) or (mai khoa)). ((hieu ve) or (hieu va)) cham hoc va danh vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky sang ((mai hoi) OR (mai khoa)). ((hieu ve) OR (hieu va)) cham hoc va danh vai cau tren.
• Adding a wildcard symbol may retrieve word variants: thu sach ky sang ((mai hoi) or (mai khoa)). ((hieu ve) or (hieu va)) cham hoc va danh vai cau tren*.