Perhaps you should try some spelling variations:
haki thuat » ki thuat
sach haki » sach bai, sach han, sach ha
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, tu cach, vu sach
y thuat » my thuat, kxy thuat, ki thuat
te sach » toc sach
sach ky » sac ky, sach ty, sach kem
do khi » doi khi, do thi, bo khi
o khi » bo khi

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 y thuat o khi ) or ( te sach ky thuat co khi ))) or ( thu sach haki thuat do khi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((( tu sach y thuat o khi ) OR ( te sach ky thuat co khi ))) OR ( thu sach haki thuat do khi )).
• Adding a wildcard symbol may retrieve word variants: (((( tu sach y thuat o khi ) or ( te sach ky thuat co khi ))) or ( thu sach haki thuat do khi ))*.