Perhaps you should try some spelling variations:
mai khoi » mai khoa, tai khoa, cac khoi
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
cam tuc » cam xuc, cam tu, nam thuc
mai hoi » dai hoi, lai hoi, mai doi
sach ty » sach tu, sach thu, xach tay
tuc va » thuc va, truc va, tuc xa
ve cam » ve cham, ve cac, va cam
vi hoc » li hoc, va hoc
hien » bien, vien, tien

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

• Performing a fuzzy search may retrieve terms with similar spellings: bo ((sach ty) or (sach y)) xang ((mai hoi) OR (mai khoi)). hieu ve cam tuc va hanh vi hoc hien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: bo ((sach ty) OR (sach y)) xang ((mai hoi) OR (mai khoi)). hieu ve cam tuc va hanh vi hoc hien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "bo ((sach ty) or (sach y)) xang ((mai hoi) OR (mai khoi)). hieu ve cam tuc va hanh vi hoc hien".
• Adding a wildcard symbol may retrieve word variants: bo ((sach ty) or (sach y)) xang ((mai hoi) OR (mai khoi)). hieu ve cam tuc va hanh vi hoc hien*.