Perhaps you should try some spelling variations:
nguyen tai » nguyen thai, nguyen thi, nguyen tac
xuyen tai » xuyen tac, truyen tai, luyen thi
cach tieu » sach thieu, cach bien, sach tien
cach tu » cach thuc
ban ve » ban va
ky thu » ly thu, ky thi, ky thuat
ve ky » va ky, ke ky
dong » dung

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((xuyen tai) or (nguyen tai)) ((cach tieu) OR (cach tu)) đe co ban ve ky thu cong dong~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((xuyen tai) OR (nguyen tai)) ((cach tieu) OR (cach tu)) đe co ban ve ky thu cong dong.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((xuyen tai) or (nguyen tai)) ((cach tieu) OR (cach tu)) đe co ban ve ky thu cong dong".
• Adding a wildcard symbol may retrieve word variants: ((xuyen tai) or (nguyen tai)) ((cach tieu) OR (cach tu)) đe co ban ve ky thu cong dong*.