Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
va nang » van nang, da nang, cam nang
van cac » van hac, van cau, van bac
cac luc » cau luc, coc luc, cac nuoc
luc van » luoc van, luu van, duc van
cua tec » cua tuc, cua toc, cua viec
ma hoi » mai hoi, xa hoi, ma hoa
v nang » vu nang, van nang, voi nang
cua te » cua tu

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 ((v nang) or (va nang)) ma hoi. hieu van cac luc van hanh vi ((cua tec) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((v nang) OR (va nang)) ma hoi. hieu van cac luc van hanh vi ((cua tec) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: toc sach ((v nang) or (va nang)) ma hoi. hieu van cac luc van hanh vi ((cua tec) or (cua te))*.