Perhaps you should try some spelling variations:
mai khoi » mai khoa, cac khoi, dai khoa
hanh tai » thanh tai, hang tai, han tai
tai khoa » da khoa, noi khoa
cau tren » cu tren, dau tren, ca tren
ky tang » ky nang, ky dang, kho tang
hieu ve » hieu va, hieu van
cam tuc » cam xuc, cam tu, nam thuc
va hanh » van hanh, va thanh, va danh
ky sang » ky nang, ky dang, duy sang
tai cau » tai cac, tai cao
so sach » so sanh, bo sach, co sach
ve cam » ve cham, ve cac, va cam
tuc va » thuc va, truc va, tuc xa

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((ky sang) or (ky tang)) ((mai khoi) OR (tai khoa)). hieu ve cam tuc va hanh tai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((ky sang) OR (ky tang)) ((mai khoi) OR (tai khoa)). hieu ve cam tuc va hanh tai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((ky sang) or (ky tang)) ((mai khoi) OR (tai khoa)). hieu ve cam tuc va hanh tai cau tren".
• Adding a wildcard symbol may retrieve word variants: so sach ((ky sang) or (ky tang)) ((mai khoi) OR (tai khoa)). hieu ve cam tuc va hanh tai cau tren*.