Lace bookmark Wave crochet pattern, Gift for book lovers, Accessory for books

Lace bookmark «Wave»
Yarn : mercerized cotton  100% 
cotton  yarn 50 g/240 m ,
 hook № 1,5  mm
scissors
The pattern is in English. It includes a step-to-step description of the process with detailed photos. There isn’t any scheme. 
The pattern is easy, but you should know some basic crochet skills. 
Level - intermediate  
There are the following crochet elements in the pattern: 
ch,  sc, tr , dtr