Perhaps you should try some spelling variations:
toc sac » toc sach, toc san, hoc sach
hang di » hang doi, hang vi, hang dien
hanh di » hanh vi, hanh de, danh di
dao va » dao van, tao va, do va
ve cac » va cac, vien cac
sac ky » cac ky, sai ky
ve ca » ve cai, ve cau, ve cua
x hoi » xa hoi, o hoi, x ho
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sac ky nang x hoi. hieu ((ve ca) or (ve cac)) dao va ((hanh di) or (hang di)) va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sac ky nang x hoi. hieu ((ve ca) OR (ve cac)) dao va ((hanh di) OR (hang di)) va thiet.
• Adding a wildcard symbol may retrieve word variants: toc sac ky nang x hoi. hieu ((ve ca) or (ve cac)) dao va ((hanh di) or (hang di)) va thiet*.