Rio Bravo Oil (SDGU) 8-K/A Changes in Registrant's Certifying Accountant

RONALD R. CHADWICK, P.C.

Certified Public Accountant

2851 South Parker Road, Suite 720

Aurora, Colorado  80014

Telephone (303)306-1967

Fax (303)306-1944

January 10, 2012

United States Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C.  20549

Re: Soton Holdings Group, Inc.

On December 15, 2011 my appointment as auditor for Soton Holdings Group, Inc. ceased. I have read Soton Holdings Group, Inc.’s statements included under Item 4.01 of its Second Amended Form 8-K/A dated January 10, 2012 and agree with such statements, insofar as they apply to me.

Very truly yours,

/s/ Ronald R. Chadwick, P.C.

Ronald R. Chadwick, P.C.

Certified Public Accountant