A nearly year-old initiative to sell tennis players' trading cards is generating vital extra income for lower earners struggling to make ends meet, its backers said.

There were no traditional sets of tennis trading cards produced at that time, though.) Statistics behind tennis cards on the secondary market display some pluses and minuses, generally speaking.

LONDON/NEW YORK (Reuters) -A nearly year-old initiative to sell tennis players' trading cards is generating vital extra income for lower earners struggling to make ends meet, its backers said.