Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hanh vai » hanh vi, hanh tai, hanh van
mai khoi » mai khoa, tai khoa, cac khoi
hanh va » hang va, hanh vi
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
ky sang » ky dang, ky tang, 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 ((ky sang) OR (ky nang)) mai khoi. 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 ((ky sang) OR (ky nang)) mai khoi. 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 ((ky sang) OR (ky nang)) mai khoi. hieu ve 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 ve cham soc va ((hanh vai) or (hanh va)) cau tren*.