Perhaps you should try some spelling variations:
hoc bien » hoc hien, hoc vien, hoa bien
xang mai » sang mai, hoang mai, giang mai
lang mai » lang dai, lang hai, lang man
va hanh » van hanh, va thanh, va danh
cam tuc » cam tu, nam thuc, dam thuc
sach ty » sach y, sach tu, sach thu
bo sach » co sach, hoc sach
hieu ve » hieu va, hieu van
vi hoc » li hoc, va hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: bo sach ty ((xang mai) OR (lang mai)) hoi. hieu ve ((cam tuc) or (cam xuc)) va hanh vi hoc bien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: bo sach ty ((xang mai) OR (lang mai)) hoi. hieu ve ((cam tuc) OR (cam xuc)) va hanh vi hoc bien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "bo sach ty ((xang mai) OR (lang mai)) hoi. hieu ve ((cam tuc) or (cam xuc)) va hanh vi hoc bien".
• Adding a wildcard symbol may retrieve word variants: bo sach ty ((xang mai) OR (lang mai)) hoi. hieu ve ((cam tuc) or (cam xuc)) va hanh vi hoc bien*.