Tetra-Quark Interpretation of X(3872) and Z_c(3900) Revisited
  In relation to the newly observed bottom-strange X^{+,-}(5568) mesons, we revisit our tetra-quark interpretation of X(3872) and Z_c(3900). It is discussed that our assignment of X^{+,-}(5568) to charged components of iso-triplet bottom partners of D_{s0}^+(2317) is compatible with the revised version of our tetra-quark interpretation of X(3872) and Z_c(3900). 
Kunihiko Terasaki
hep-ph nucl-th