Answer:
The below displays subjects with its associated books. This we would display using <UL> 
English 
Coursebook 
Workbook 
Mathematics 
Lab manual 
Course book 
Science 
Scrap book 
Course book 
 <UL> 
 <LI>English 
 <UL> 
 <LI>Course book</LI> 
 <LI>Workbook</LI> 
 </UL> 
 </LI> 
 <LI>Maths 
 <UL> 
 <LI>Lab manual</LI> 
 <LI>Course book</LI> 
 </UL> 
 </LI> 
<LI>Science 
 <UL> 
 <LI>Scrap book</LI> 
 <LI>Course book</LI> 
 </UL> 
 </LI> 
</UL> 
Here <UL> tag creates un ordered list and one another <UL> tag inside <LI> created nested list. This is how a nested unordered lists needs to be created.