They arrived in the US aboard the old TWA airlines, likely under the Displaced Persons Act which allowed about a half million displaced people to settle in the US after WW II. I have several friends (Croatians) who lived in DP camps until the early 1960s before they came to the US.
Arrival Date: 13 Mar 1957
Port of Depaturue Hamburg Germany
Milos age (not legible)
Ingeborg age (not legible)
Rajko age not legible
Danilo age not legible
Under the column on the manifest for Nation, are the letters STL, which means stateless.
Rajko (sounds like rye koh, thus the change he made to Riko) is from the word raj, which means heavan, KO is a dimnutive.
It is hard to say where they came from in Yugoslavia (which was a short lived country 1920-1991) as Serbs lived in Serbia proper, Bosnia, Croatia and Montenegro.
But from what I see of earlier immigration of VEŠKOVIĆ (sounds like veshkohvich) to the US they were coming from Dalmatian Croatia, part of which is now Montenegro.
There are about a dozen listings in the current online Croatia phone book, most in the Dalmatian region.
http://imenik.tportal.hr/show?action=pretraga&type=bijel...The Serbia phone book is also online but a bit more involved as you must search county by county
http://www.telekom.rs/whitepages/searchpage.asp2 other VESKOVIC families arrived in the 1950s from Bremen Germany aboard US troop ships (the normal mode of travel for DPs in those days), with one family going to Cincinnati the other to NYC
A record is found at the Mauthausen Concentration Camp for the death of Radovan VESKOVIC DOB 1922, DOD 1943
Perhaps the best place for your query is at the Serbia based genealogy web page
http://www.rodoslovlje.com/Robert Jerin
Croatian Heritage Museum
Cleveland Ohio