Perhaps you should try some spelling variations:
dan khai » dang khai, van khai, dang khoi
khai cau » khai cac, phan cau, hai chau
cau tren » cu tren, dau tren, ca tren
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
hieu va » lieu va, hieu qua
ma hoi » mai hoi, xa hoi, ma hoa
va cam » va cham, va cac, va cao
tuc va » thuc va, truc va, duc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang ma hoi. hieu va cam ((tuc va) or (tuc xa)) dan khai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ma hoi. hieu va cam ((tuc va) OR (tuc xa)) dan khai cau tren.
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ma hoi. hieu va cam ((tuc va) or (tuc xa)) dan khai cau tren*.