Perhaps you should try some spelling variations:
nang doc » nang luc
dau tren » dau tien, dat tren, dau tieng
doc hoc » duoc hoc, toc hoc, duc hoc
sach ky » sach y, sach ty, sach kem
va hanh » van hanh, va thanh, va danh
hanh ve » hanh vi, hanh va, hanh kem
ve cham » va cham, ve chat, vu cham
sac ky » cac ky, sai ky
ve cac » va cac, vien cac
xuc va » duc va, tuc va, luc va
ve dau » va dau, ve du, ke dau

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 doc hoc. hieu ((ve cham) or (ve cac)) xuc va hanh ve dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sac ky)) nang doc hoc. hieu ((ve cham) OR (ve cac)) xuc va hanh ve dau tren.
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sac ky)) nang doc hoc. hieu ((ve cham) or (ve cac)) xuc va hanh ve dau tren*.