Perhaps you should try some spelling variations:
khan thong » khap thong, khau thong, nhan thong
khac thong » khac thuong, khac trong, khap thong
cach khoa » bach khoa, cac khoa, cac khoan
khoa khac » khoa kham, khoanh khac, khoa hoc
hanh noi » ha noi, hanh vi, nang noi
noi thuc » choi thuc, nghi thuc, cuoi thuc
thuc dac » thuoc dac, thuc dan, thuc day
kho khan » khoa kham, khoa than
sach tri » sach tai, sach tren, sach truc
hoc cach » hoc cac, hoc sach, cuoc cach
tu hanh » du hanh, lu hanh, thuc hanh
dac kho » dac khoa, dac khao, dac cho
su sach » so sach, vu sach
tri hoc » triet hoc, tri thuc, thai hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu hanh noi thuc dac kho khan thong ) or ( su sach tri hoc cach khoa khac thong ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu hanh noi thuc dac kho khan thong ) OR ( su sach tri hoc cach khoa khac thong )).
• Adding a wildcard symbol may retrieve word variants: (( tu hanh noi thuc dac kho khan thong ) or ( su sach tri hoc cach khoa khac thong ))*.