diff --git a/docs/type-system/interfaces.md b/docs/type-system/interfaces.md
index 9610ce0..6e7501f 100644
--- a/docs/type-system/interfaces.md
+++ b/docs/type-system/interfaces.md
@@ -103,7 +103,7 @@ $humanType = new ObjectType([
 ```
 
 In this case field definitions are created only once (as a part of Interface Type) and then 
-re-used by all interface implementors. It can save several microseconds and memory + ensures that 
+re-used by all interface implementors. It can save several microseconds and kilobytes + ensures that 
 field definitions of Interface and implementors are always in sync.
 
 Yet it creates a problem with resolution of such fields. There are two ways how shared fields could 
diff --git a/docs/type-system/lists-and-nonnulls.md b/docs/type-system/lists-and-nonnulls.md
index f061bb2..89a5fde 100644
--- a/docs/type-system/lists-and-nonnulls.md
+++ b/docs/type-system/lists-and-nonnulls.md
@@ -21,13 +21,13 @@ $userType = new ObjectType([
 ]);
 ```
 
-Resolvers for such fields are expected to return `array` or instance of `Traversable` interface 
-(`null` is allowed by default too). 
+Resolvers for such fields are expected to return `array` or instance of PHP internal `Traversable` 
+interface (`null` is allowed by default too). 
 
 If returned value is not of one of these types - **graphql-php** will add an error to result 
 and set field value to `null` (only if field is nullable, see below for non-null fields).
 
-# Non-Null types
+# Non-Null fields
 By default in GraphQL every field can have `null` value. To indicate that some field always 
 returns `non-null` value - use `GraphQL\Type\Definition\Type::nonNull()` modifier: