Perhaps you should try some spelling variations:
thoi nghiem » thi nghiem, khoi nghiep, thuc nghiem
vao nghien » va nghien, tam nghien, va nghiep
dau nghien » va nghien, tam nghien
cach thoi » cac thoi, cach thuc, cach noi
nghiem te » nghiem de, nghiem ve, nghiem tien
thu sach » tu sach, thuat sach, thuoc sach
tu cach » tu 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 cach thoi nghiem te hoc ) or ( thu sach ((vao nghien) OR (dau nghien)) te hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu cach thoi nghiem te hoc ) OR ( thu sach ((vao nghien) OR (dau nghien)) te hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( tu cach thoi nghiem te hoc ) or ( thu sach ((vao nghien) OR (dau nghien)) te hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( tu cach thoi nghiem te hoc ) or ( thu sach ((vao nghien) OR (dau nghien)) te hoc ))*.