Perhaps you should try some spelling variations:
vanh tai » van tai, hanh tai, anh tai
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
va vanh » va van, va danh, va hanh
van cau » van dau, van hau, van chat
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
su sach » so sach, vu sach
ma hoi » mai hoi, xa hoi, ma hoa
cau tu » dau tu, cau truc
tai va » thai va, mai va, tri va
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: ((((te sach) OR (toc sach))) or (su sach)) ty nang ma hoi. hieu van cau tu va vanh tai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((te sach) OR (toc sach))) OR (su sach)) ty nang ma hoi. hieu van cau tu va vanh tai va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((te sach) OR (toc sach))) or (su sach)) ty nang ma hoi. hieu van cau tu va vanh tai va thiet".
• Adding a wildcard symbol may retrieve word variants: ((((te sach) OR (toc sach))) or (su sach)) ty nang ma hoi. hieu van cau tu va vanh tai va thiet*.