The Barclays Premier League quartet have all inquired about the Republic of Ireland international who scored 25 goals for the Royals last season.
Long game: Reading won't cash in on striker Shane Long unless his ?10million valuation is met
Sunderland have been the highest bidders so far with a ?7m offer for the 24-year-old.
But Reading are adamant they want ?10m for the player described as 'world class' by chairman John Madejski after their Championship final play-off defeat by Swansea in May.
No holding back: Reading insists they won't stand in the Republic of Ireland star's way for the right price
Reading manager Brian McDermott is resigned to losing Long, who signed from Cork City six years ago.
He said: 'If a Premier League club comes in and we feel it is the right offer there's nothing we can do.'
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?Explore more:People: John Madejski, Brian McDermott Places: Newcastle, Republic of Ireland
Source: Daily Mail
Source: Daily Mail