po prostu

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Note added at 2003-04-21 20:19:06 (GMT)
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new types of postcards were put into circulation

http://www.byegm.gov.tr/yayinlarimiz/NEWSPOT/1999/mar/N15.ht...

all postcards, issued and put into circulation

http://www.infotel.bg/cpt/winen/b72-1.htm

"These postcard series had touristic scenes on them and were
put into circulation in 1965, 1968, 1970, 1972 and 1974."

'put into circulation' jest często używane w srodowisku filatelistycznym właśnie dla oznaczenia 'włączyć do obiegu'. Na przykład:
" The Board retained one sheet as the Imprimatur and the other five sheets were either destroyed or perforated and put into circulation. "

i think introduce sounds a little better

In late 1996, the Treasury began issuing a series of Federal Reserve notes containing new features that make the notes harder to counterfeit. The Treasury introduced the modified notes in order of decreasing denomination - - the $100 bill appeared in March 1996, the $50 bill in October 1997, the $20 bill in September 1998, and the $10 and $5 bills in May 2000. The most noticeable modification was a larger, slightly off-center portrait that incorporates more detail, thereby making the bill harder to counterfeit. For the benefit of persons with impaired vision, the back of the modified $50, $20, $10 and $5 bills features numerals larger than those on older currency.

zresztą po polsku też wchodzą a nie są włączane do obiegu