Perhaps you should try some spelling variations:
ban thai » ban than, ban thi, ban tai
dua tren » dung tren
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cac vuc » cac nuoc, cac vung, cac cuoc
vuc van » duc van, luc van, thuc van
cua tu » cua tuc, cua su, cua cu
x hoi » xa hoi, o hoi, 5 hoi

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 ty nang ((x hoi) OR (x ho)). lieu va cac vuc van ban thai ((dua tren) or (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ((x hoi) OR (x ho)). lieu va cac vuc van ban thai ((dua tren) OR (cua tu)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((x hoi) OR (x ho)). lieu va cac vuc van ban thai ((dua tren) or (cua tu))".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((x hoi) OR (x ho)). lieu va cac vuc van ban thai ((dua tren) or (cua tu))*.