Here is a list of these comics translated into English :

http://en.wikipedia.org/wiki/List_of_Spike_and_Suzy_books_in_English

The Willy & Wanda and Bob & Bobette series contain older yet better stories, of the Spike & Suzy series I would recommend "Highland Games", also an older story still written and drawn by original author Willy Vandersteen.

The more recent releases can still be found on sites such as Amazon or Ebay.

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