Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
luc ngan » luc nganh, luc nhan, luat ngan
sach ty » sach y, sach tu, sach thu
hang vi » hang va, hang di, khang voi
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
ve cau » ke cau, va cau, le cau
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 ty nang xa hoi. hieu ((ve cau) OR (ve cac)) luc ngan ((hang vi) or (hanh vi)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang xa hoi. hieu ((ve cau) OR (ve cac)) luc ngan ((hang vi) OR (hanh vi)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang xa hoi. hieu ((ve cau) OR (ve cac)) luc ngan ((hang vi) or (hanh vi)) cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang xa hoi. hieu ((ve cau) OR (ve cac)) luc ngan ((hang vi) or (hanh vi)) cau tren*.