Myself and others made a number of earlier reports on the subject, before it was clear who was providing the weapons, with my first post on the subject back in January 16th followed by two more updates as I discovered more information
From February James Miller and Scott Lucas of EA Worldview also produced a number of posts on the subject
Michael Weiss examined the appearance of these weapons on February 20th with "Who just started arming Syria rebels?".
As part of my research into the weapons in questions I've put together a number of Youtube playlists with all the videos I've come across showing these weapons in the hands of the opposition:
It appears Croatian weapons aren't the only recently sighted foreign weapons in Syria, with Chinese MANPADS (surface to air missiles), and French rockets appearing on the field in recent weeks.