Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hanh vai » hanh vi, hanh tai, hanh van
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
mai khoi » mai khoa, tai khoa, cac khoi
ky sang » ky dang, ky tang, duy sang
hanh va » hang va, hanh vi
tu sach » thu sach, su sach, te sach
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 ((ky sang) or (ky nang)) mai khoi. hieu van 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 ((ky sang) OR (ky nang)) mai khoi. hieu van cham soc va ((hanh vai) OR (hanh va)) cau tren.
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky sang) or (ky nang)) mai khoi. hieu van cham soc va ((hanh vai) or (hanh va)) cau tren*.