Perhaps you should try some spelling variations:
thien van » thi van
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, lieu va, hieu ve
tan hanh » tan thanh, tang hanh, toan hanh
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
hac duc » hoc duc, ha duc, thach duc
ma hoi » mai hoi, ma hoa, me hoi
vi cua » vai cua, di cua
cua tu » cua tuc, cua su, cua cu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty nang ((ma hoi) OR (xa hoi)). ((hieu van) OR (thien van)) hac duc tan hanh vi cua tu~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty nang ((ma hoi) or (xa hoi)). ((hieu van) OR (thien van)) hac duc tan hanh vi cua tu~".
• Adding a wildcard symbol may retrieve word variants: toc sach ty nang ((ma hoi) or (xa hoi)). ((hieu van) OR (thien van)) hac duc tan hanh vi cua tu*.