For information on remittances sent to Cuba by Cuban Americans, see:

“Cuba: US Restrictions on Travel and Remittances.” Congressional Research Service Report for Congress, Updated August 30, 2006.
http://www.fas.org/sgp/crs/row/RL31139.pdf

“Remittances to Cuba: A Survey of Methods and Estimates” by Sergio Díaz-Briquets and Jorge Pérez-López in Cuba In Transition (Volume 15), Association for the Study of the Cuban Economy, 2005.
http://lanic.utexas.edu/project/asce/pdfs/volume15/pdfs/diazbriquetsperezlopez.pdf

“Cuban Americans on Remittances and the Embargo” by Frances Spiegel. Florida International University, M.A. Thesis, 2004.
http://lacc.fiu.edu/centers_institutes/cri/Frances_Thesis.pdf