The "TBA" on July 21 appears to be Turkey again per the article: http://www.bbc.co.uk/sport/0/formula1/20614283 Pete

2013 FORMULA 1 CALENDAR
17 March - Australia (Melbourne)
24 March - Malaysia (Sepang)
14 April - China (Shanghai)
21 April - Bahrain (Sakhir)
12 May - Spain (Barcelona)
26 May - Monaco
9 June - Canada (Montreal)
30 June - Britain (Silverstone)
7 July - Germany (Nurburgring/Hockenheim)
21 July - TBA
28 July - Hungary (Hungaroring)
25 August - Belgium (Spa-Francorchamps)
8 September - Italy (Monza)
22 September - Singapore (Marina Bay)
6 October - Korea (Yeongam) *
13 October - Japan (Suzuka)
27 October - India (Buddh International)
3 November - Abu Dhabi (Yas Marina)
17 November - United States (Austin)
24 November - Brazil (Interlagos)
* Subject to confirmation