Perhaps you should try some spelling variations:
dat tren » dat trong, dua tren
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va

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 ky nang x ho. hieu va cac tuc va dan vi ((cau tren) or (dat tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x ho. hieu va cac tuc va dan vi ((cau tren) OR (dat tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x ho. hieu va cac tuc va dan vi ((cau tren) or (dat tren))*.