Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
cham hoc » cham soc, chat hoc, cham hoi
lang van » dang van, tang van, hoang van
thu sach » thuat sach, thuoc sach, thu hoach
lang ha » long ha
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
va hanh » van hanh, va thanh, va danh
tu sach » su sach, te sach, tu cach
vi cau » va cau, ve cau, di cau

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) OR (thu sach)) y ((lang ha) or (lang van)) hoi. hieu vu cham hoc va hanh vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) y ((lang ha) OR (lang van)) hoi. hieu vu cham hoc va hanh vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) y ((lang ha) or (lang van)) hoi. hieu vu cham hoc va hanh vi cau tren".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) y ((lang ha) or (lang van)) hoi. hieu vu cham hoc va hanh vi cau tren*.