i think the main reason large river rocks are recommended is that lots of frogs have problems with ingesting substrates and if you use smaller rocks or gravel you risk impaction or blockage if he accidentally eats some... plus they are easy to keep clean... if you have several pet stores near you, go in and talk to the employees about adopting a Whites.. kinda depends on the area i suppose.. at the store i work at we get quite a few customers who come in wanting to abandon reptiles and amphibians.. mostly due to children who lost interest.. or they didnt really realize how much care they would require... see if they employees can keep an eye out for you... sometimes the employees themselves have one and are bored with it.. thats how i got mine.. if your area has a herpetological society, they might be able to point you in the right direction also... as far as books go.. "guide to owning a whites treefrogs" by john corborn is probably going to be at any local pet store.. it has a decent amount of info.. thats what i supplemented my internet reading with when i got my whites..
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my pets: clown treefrogs, reed frogs, big eyed treefrogs, tiger leg monkey frogs, gray treefrogs, milk frogs, cuban treefrogs, whites tree frog, green treefrogs, squirrel treefrogs, blue webbed gliding treefrog, chameleon treefrogs?, dusky salamanders, tiger salamander, veiled chameleon, box turtles, mud turtle, map turtle, yellowbelly slider, florida softshell, two saltwater tanks, four cats, two chinchillas, and a boyfriend.