Perhaps you should try some spelling variations:
toc sac » toc sach, toc san, hoc sach
nang xa » nang x, lang xa, nang ma
va hanh » van hanh, va thanh, va danh
sac ky » cac ky, sai ky
ve cac » va cac, vien cac
dao va » dao van, tao va, do va
ve ca » ve cai, ve cau, ve cua
vi su » va su, ki su, oi su
ve su » va su

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sac ky nang xa hoi. hieu ((ve ca) or (ve cac)) dao va hanh ((vi su) OR (ve su)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sac ky nang xa hoi. hieu ((ve ca) OR (ve cac)) dao va hanh ((vi su) OR (ve su)) triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sac ky nang xa hoi. hieu ((ve ca) or (ve cac)) dao va hanh ((vi su) OR (ve su)) triet*".