diff --git a/src/SUMMARY.md b/src/SUMMARY.md
index 1bd5e42..e60b82d 100644
--- a/src/SUMMARY.md
+++ b/src/SUMMARY.md
@@ -1,77 +1,77 @@
 # Summary
 
 - [Why Exercise.rs](why-exercise.md)
-- [Variables](variables.md)
-- [Basic Types](basic-types/intro.md)
+- [Variables todo](variables.md)
+- [Basic Types todo](basic-types/intro.md)
   - [Numbers](basic-types/numbers.md)
   - [Char, Bool and Unit](basic-types/char-bool-unit.md)
   - [Statements and Expressions](basic-types/statements-expressions.md)
   - [Functions](basic-types/functions.md)
-- [Ownership and Borrowing](ownership/intro.md)
+- [Ownership and Borrowing todo](ownership/intro.md)
   - [Ownership](ownership/ownership.md)
   - [Reference and Borrowing](ownership/borrowing.md)
-- [Compound Types](compound-types/intro.md)
+- [Compound Types todo](compound-types/intro.md)
   - [string and slice](compound-types/string-slice.md)
   - [tuple](compound-types/tuple.md)
   - [struct](compound-types/struct.md)
   - [enum](compound-types/enum.md)
   - [array](compound-types/array.md)
-- [Flow Control](flow-control.md)
-- [Pattern Match](pattern-match/intro.md)
+- [Flow Control todo](flow-control.md)
+- [Pattern Match todo](pattern-match/intro.md)
   - [match, if let](pattern-match/match-iflet.md)
   - [Option destructing](pattern-match/option.md)
   - [Patterns](pattern-match/patterns.md)
-- [Method](method.md)
-- [Generics and Traits](generics-traits/intro.md)
+- [Method todo](method.md)
+- [Generics and Traits todo](generics-traits/intro.md)
   - [Generics](generics-traits/generics.md)
   - [Traits](generics-traits/traits.md)
   - [Trait Object](generics-traits/trait-object.md)
   - [Advance Traits](generics-traits/advance-traits.md)
-- [Collection Types](collections/intro.md)
+- [Collection Types todo](collections/intro.md)
   - [Vector](collections/vector.md)
   - [HashMap](collections/hashmap.md)
-- [Type Conversion](type-conversion.md)
-- [Result and panic](result-panic/intro.md)
+- [Type Conversion todo](type-conversion.md)
+- [Result and panic todo](result-panic/intro.md)
   - [panic!](result-panic/panic.md)
   - [result and ?](result-panic/result.md)
-- [Crate and module](crate-module/intro.md)
+- [Crate and module todo](crate-module/intro.md)
   - [Crate](crate-module/crate.md)
   - [Module](crate-module/module.md)
   - [use and pub](crate-module/use-pub.md)
-- [Comments and Docs](comments-docs.md)
-- [Formatted output](formatted-output.md)
-- [Lifetime](lifetime/intro.md)
+- [Comments and Docs todo](comments-docs.md)
+- [Formatted output todo](formatted-output.md)
+- [Lifetime todo](lifetime/intro.md)
   - [basic](lifetime/basic.md)
   - [&'static and T: 'static](lifetime/static.md)
   - [advance](lifetime/advance.md)
-- [Functional programing](functional-programing/intro.md)
+- [Functional programing todo](functional-programing/intro.md)
   - [Closure](functional-programing/cloure.md)
   - [Iterator](functional-programing/iterator.md)
-- [newtype and Sized](newtype-sized.md)
-- [Smart pointers](smart-pointers/intro.md)
+- [newtype and Sized todo](newtype-sized.md)
+- [Smart pointers todo](smart-pointers/intro.md)
   - [Box](smart-pointers/box.md)
   - [Deref](smart-pointers/deref.md)
   - [Drop](smart-pointers/drop.md)
   - [Rc and Arc](smart-pointers/rc-arc.md)
   - [Cell and RefCell](smart-pointers/cell-refcell.md)
-- [Weak and Circle reference](weak.md)
-- [Self referential](self-referential.md)
-- [Threads](threads/intro.md)
+- [Weak and Circle reference todo](weak.md)
+- [Self referential todo](self-referential.md)
+- [Threads todo](threads/intro.md)
   - [Basic using](threads/basic-using.md)
   - [Message passing](threads/message-passing.md)
   - [Sync](threads/sync.md)
   - [Atomic](threads/atomic.md)
   - [Send and Sync](threads/send-sync.md)
-- [Global variables](global-variables.md)
-- [Errors](errors.md)
-- [unsafe](unsafe.md)
-- [macro](macro.md)
-- [Tests](tests/intro.md)
+- [Global variables todo](global-variables.md)
+- [Errors todo](errors.md)
+- [unsafe todo](unsafe.md)
+- [macro todo](macro.md)
+- [Tests todo](tests/intro.md)
   - [Write Tests](tests/write-tests.md)
   - [Benchmark](tests/benchmark.md)
   - [Unit and Integration](tests/unit-integration.md)
   - [Assertions](tests/assertions.md)
-- [Async/Await](async/intro.md)
+- [Async/Await todo](async/intro.md)
   - [async and await!](async/async-await.md)
   - [Future](async/future.md)
   - [Pin and Unpin](async/pin-unpin.md)