Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
hoc luoc » hoc nuoc, hoc duoc, hoc quoc
luoc gia » quoc gia, luc gia, luong gia
ty hang » ly hang, ty xang, thi hang
cao hoi » cau hoi, co hoi, cao hoc
van hoc » van hoa
vi cau » va cau, di cau, viet cau
ve cau » ke cau, va cau, ve cac

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 ((ty hang) or (ky nang)) cao hoi. hieu van hoc luoc gia thanh ((vi cau) OR (ve cau)) treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ty hang) OR (ky nang)) cao hoi. hieu van hoc luoc gia thanh ((vi cau) OR (ve cau)) treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ty hang) or (ky nang)) cao hoi. hieu van hoc luoc gia thanh ((vi cau) OR (ve cau)) treo".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ty hang) or (ky nang)) cao hoi. hieu van hoc luoc gia thanh ((vi cau) OR (ve cau)) treo*.