Perhaps you should try some spelling variations:
cham hoc » cham soc, chat hoc, cham hoi
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, mang xa, ang xa
hieu vu » hieu ve, hieu su, dieu vu
hieu va » lieu va, hieu qua
hoc van » hoc dan, hoc va, hoc vat
vi cua » vai cua
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty xang xa hoi. ((hieu vu) or (hieu va)) cham hoc van hanh ((vi cua) OR (di cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty xang xa hoi. ((hieu vu) OR (hieu va)) cham hoc van hanh ((vi cua) OR (di cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty xang xa hoi. ((hieu vu) or (hieu va)) cham hoc van hanh ((vi cua) OR (di cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty xang xa hoi. ((hieu vu) or (hieu va)) cham hoc van hanh ((vi cua) OR (di cua)) tre*.