diff --git a/src/epub_converter/html_epub_preprocessor.py b/src/epub_converter/html_epub_preprocessor.py
index e2fe136..627d1f1 100644
--- a/src/epub_converter/html_epub_preprocessor.py
+++ b/src/epub_converter/html_epub_preprocessor.py
@@ -96,13 +96,11 @@ def _wrap_strings_with_p(chapter_tag):
     for node in chapter_tag:
         if isinstance(node, NavigableString):
             content = str(node)
-            content = re.sub(r"([\n\t\xa0])", " ", content)
-            # remove spaces at the beginning and at the end of the string:
-            content = content.strip()
+            content = re.sub(r"([\s\xa0])", " ", content).strip()
             if content:
-                tag = chapter_tag.new_tag("p")
-                tag.append(str(node))
-                node.replace_with(tag)
+                p_tag = chapter_tag.new_tag("p")
+                p_tag.append(str(node))
+                node.replace_with(p_tag)
 
 
 def _remove_headings_content(content_tag, title_of_chapter: str):
@@ -146,6 +144,7 @@ def _tags_to_correspond_livecarta_tag(chapter_tag):
         for key in reg_key:
             tags = chapter_tag.find_all(re.compile(key))
             for tag in tags:
+                # todo can cause appearance of \n <p><p>...</p></p> -> <p>\n</p> <p>...</p> <p>\n</p> (section)
                 tag.name = to_replace_value
 
 def _unwrap_tags(chapter_tag):
@@ -300,8 +299,6 @@ def _clean_wiley_block(block):
         h.insert_before(BeautifulSoup(features="lxml").new_tag("br"))
 
 
-
-
 def _preprocess_block_tags(chapter_tag: Tag):
     """Function preprocessing <block> tags"""
     for block in chapter_tag.find_all("blockquote", attrs={"class": re.compile("feature[1234]")}):
@@ -323,6 +320,13 @@ def _preprocess_block_tags(chapter_tag: Tag):
         _wrap_tag_with_table(chapter_tag, future_block, bg_color=color)
 
 
+def _class_removing(chapter_tag):
+    for tag in chapter_tag.find_all(recursive=True):
+        if tag.attrs.get("class") \
+                and (tag.attrs.get("class") not in ["link-anchor", "footnote-element"]):
+            del tag.attrs["class"]
+
+
 def prepare_content(title_str: str, content_tag: BeautifulSoup, remove_title_from_chapter: bool) -> str:
     """
     Function finalise processing/cleaning content
@@ -368,9 +372,6 @@ def prepare_content(title_str: str, content_tag: BeautifulSoup, remove_title_fro
     _preprocess_div_tags(content_tag)
     _preprocess_block_tags(content_tag)
 
-    # 5. remove classes that were created by converter
-    for tag in content_tag.find_all(recursive=True):
-        if hasattr(tag, "attrs") and tag.attrs.get("class") \
-                and (tag.attrs.get("class") not in ["link-anchor", "footnote-element"]):
-            del tag.attrs["class"]
+    # 5. remove classes that weren't created by converter
+    _class_removing(content_tag)
     return str(content_tag)