Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cham duc » pham duc, cham soc, pham duy
tang xa » trang xa, tang ma, lang xa
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
va danh » va dinh, va dan, va hanh
dau cua » day cua, cau cua, dan cua
y tang » ky tang, 6 tang, 7 tang

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) y tang xa hoi. hieu ve cham duc va danh ((dau cua) OR (dai cua)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) y tang xa hoi. hieu ve cham duc va danh ((dau cua) OR (dai cua)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) y tang xa hoi. hieu ve cham duc va danh ((dau cua) OR (dai cua)) triet".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) y tang xa hoi. hieu ve cham duc va danh ((dau cua) OR (dai cua)) triet*.