Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
ty nang » ky nang, ty xang, ty hang
sach ty » sach y, sach tu, sach thu
van cau » van dau, van hau, van chat
cau duc » cao duc, cau luc, chu duc
va hanh » van hanh, va thanh, va danh
ma hoi » mai hoi, xa hoi, me hoi
vi cu » vi xu, vi du
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach ty nang ((ma hoi) or (ma hoa)). hieu van cau duc va hanh ((vi cu) OR (vi su)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ty nang ((ma hoi) OR (ma hoa)). hieu van cau duc va hanh ((vi cu) OR (vi su)) tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ty nang ((ma hoi) or (ma hoa)). hieu van cau duc va hanh ((vi cu) OR (vi su)) tren*".