Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban danh » ban doanh, ban hanh, ban dan
duc ban » duc tan, duc van, dua ban
hoi cua » hoi chuc
hai cua » thai cua, dai cua, lai cua
qua cac » cua cac
cac duc » cac du, cao duc, cac dac
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (thu hoach)) ty nang ma hoi. hieu qua cac duc ban danh ((hai cua) or (hoi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (thu hoach)) ty nang ma hoi. hieu qua cac duc ban danh ((hai cua) OR (hoi cua)) tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (thu hoach)) ty nang ma hoi. hieu qua cac duc ban danh ((hai cua) or (hoi cua)) tre*.