RADIO INTERFEROMETRIC PLANET SEARCH. II. CONSTRAINTS ON SUB-JUPITER-MASS COMPANIONS TO GJ 896A. - BOWER, GEOFFREY C.; BOLATTO, ALBERTO; FORD, ERIC B.; FRIES, ADAM; KALAS, PAUL; SANCHEZ, KAROL; SANDERBECK, PHOEBE; VISCOMI, VINCENT (Astrophysical Journal, 2011)