Perhaps you should try some spelling variations:
nang noi » nang doc
dat tren » dat trong, dua tren
noi hoc » hoi hoc, voi hoc, noi khoa
sach ky » sac ky, sach ty, sach kem
vu kham » vu khanh
va hanh » van hanh, va thanh, va danh
hanh ve » hanh vi, hanh va, hanh kem
ve cham » va cham, ve chat, vu cham
luc va » duc va, tuc va, loc va
ve dat » de dat, va dat, ve dao

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 (sach y)) nang noi hoc. hieu ((ve cham) or (vu kham)) luc va hanh ve dat tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sach y)) nang noi hoc. hieu ((ve cham) OR (vu kham)) luc va hanh ve dat tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) OR (sach y)) nang noi hoc. hieu ((ve cham) or (vu kham)) luc va hanh ve dat tren".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) OR (sach y)) nang noi hoc. hieu ((ve cham) or (vu kham)) luc va hanh ve dat tren*.