Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
mai khoi » mai khoa, cac khoi, dai khoa
hanh vai » hanh vi, hanh tai, hanh van
tai khoa » da khoa, noi khoa
hanh va » hang va, hanh vi
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
ty sang » ty xang, ty hang, duy sang
ve cham » va cham, ve chat, vu cham
soc va » hoc va, loc va, doc va

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 sang ((mai khoi) OR (tai khoa)). hieu ve cham soc va ((hanh vai) or (hanh va)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty sang ((mai khoi) OR (tai khoa)). hieu ve cham soc va ((hanh vai) OR (hanh va)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty sang ((mai khoi) OR (tai khoa)). hieu ve cham soc va ((hanh vai) or (hanh va)) cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ty sang ((mai khoi) OR (tai khoa)). hieu ve cham soc va ((hanh vai) or (hanh va)) cau tren*.