Perhaps you should try some spelling variations:
nang duc » nang luc, nang doc, nang du
cham duc » pham duc, cham soc, pham duy
cau tren » cu tren, dau tren, ca tren
duc hoc » duoc hoc, luc hoc, du hoc
sach ky » sach y, sach ty, sach kem
ve cham » va cham, ve chat, vu cham
hanh va » hang va
hieu ve » hieu va, hieu van
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) or (sac ky)) nang duc hoc. hieu ve cham duc va ((hanh va) or (hanh vi)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sac ky)) nang duc hoc. hieu ve cham duc va ((hanh va) OR (hanh vi)) cau tren.
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sac ky)) nang duc hoc. hieu ve cham duc va ((hanh va) or (hanh vi)) cau tren*.