Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
la tren » loai tren, dua tren, dat tren
cac tuc » cac toc, cac tu, cac tac
hieu ve » hieu va, hieu van
cu tren » tu tren, dua tren
cao hoi » cau hoi, co hoi, cao hoc
v nang » va nang, vu nang, van nang
y nang » ky nang, ly nang, may nang
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau
ve cac » va cac, vien cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((y nang) OR (v nang)) cao hoi. hieu ve cac tuc va dan ca ((la tren) or (cu tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y nang) OR (v nang)) cao hoi. hieu ve cac tuc va dan ca ((la tren) OR (cu tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y nang) OR (v nang)) cao hoi. hieu ve cac tuc va dan ca ((la tren) or (cu tren))".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y nang) OR (v nang)) cao hoi. hieu ve cac tuc va dan ca ((la tren) or (cu tren))*.