Many music stores carry books, but you can find them through the internet at music stores, books stores and auction sites.
Tabs are also available from many sources on the internet. I've provided a couple below. Chordie has the most and on many of them you can choose the instrument and the tuning in a box on the right.
There are many online music sites that offer ukulele tabs. Youtube also has videos with hands on explanations of different tabs. Local music stores will sell ukulele tab books as well.
Ukulele Tabs web site has it at the link below.
The Ukulele Tabs site linked below has them.
The link below will provide the tabs for playing Bubbly on the ukulele.
You can find the tabs and chords at Ukulele Hunt at the link below.
According to "Whois" the web site ukulele-tabs.com resides on a server in Switzerland.
Ukulele tabs are in the international language of music. They have no language. Instructions and the words to the songs vary in language, but music is universal. The web site Ukuleletabs.com appears to be Swiss.
The link below takes you to a site that has the tabs you are looking for.
Mainly traditional music symbols or tabs.
There are copyright laws. Depending on the songs the tabs are legal to post in some countries and not legal in others.
The link below will take you to one version.
The link below will take you to a site with the tabs online.