Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
nang mai » nang ma, nang tai, lang mai
mai hoi » mai khoi, dai hoi, lai hoi
va pham » van pham, va phat, va phap
va hang » van hang, va nang, va lang
hai cua » thai cua, hoi cua, lai cua
y nang » ky nang, ly nang, v nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (doc sach)) y nang mai hoi. lieu va pham duc va hang ((hai cua) OR (dai cua)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) y nang mai hoi. lieu va pham duc va hang ((hai cua) OR (dai cua)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) y nang mai hoi. lieu va pham duc va hang ((hai cua) OR (dai cua)) triet".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) y nang mai hoi. lieu va pham duc va hang ((hai cua) OR (dai cua)) triet*.